Method for transceiving signal in a wireless communication system and apparatus for the same

ABSTRACT

Disclosed is a method for transmitting/receiving a signal in a wireless communication system supporting narrow-band (NB)-LTE, which is performed a terminal, including: receiving a narrow band synchronization signal from a base station; acquiring time synchronization and frequency synchronization with the base station based on the narrow band synchronization signal and detecting an identifier of the base station; and receiving a narrow band broadcast channel from the base station based on the detected identifier of the base station.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. § 119(e), this application claims the benefit ofU.S. Provisional Patent Application Nos. 62/387,372, filed on Dec. 24,2015, 62/277,909, filed on Jan. 12, 2016 and 62/290,892, filed on Feb.3, 2016, the contents of which are all hereby incorporated by referenceherein in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a wireless communication system, andmore particularly, to a method for transmitting/receiving a signal in awireless communication system supporting narrowband (NB)-LTE and anapparatus for supporting the same.

Discussion of the Related Art

Mobile communication systems have been developed to provide voiceservices while ensuring the activity of a user. However, the mobilecommunication systems have been expanded to their regions up to dataservices as well as voice. Today, the shortage of resources is causeddue to an explosive increase of traffic, and more advanced mobilecommunication systems are required due to user's need for higher speedservices.

Requirements for a next-generation mobile communication system basicallyinclude the acceptance of explosive data traffic, a significant increaseof a transfer rate per user, the acceptance of the number ofsignificantly increased connection devices, very low end-to-end latency,and high energy efficiency. To this end, research is carried out onvarious technologies, such as dual connectivity, massive Multiple InputMultiple Output (MIMO), in-band full duplex, Non-Orthogonal MultipleAccess (NOMA), the support of a super wideband, and device networking.

SUMMARY OF THE INVENTION

An object of the preset invention is to provide a pattern and/or ascheme in which a synchronization signal and a radio resource of abroadcast channel are mapped, which may be used for characteristics anda purpose of a narrowband LTE system in a wireless communication systemsupporting the narrowband LTE system.

Further, another object is to provide a method fortransmitting/receiving a synchronization signal, a broadcast channel,and the like in an NB-LTE system considering a frame structure typedefined in LTE.

The technical objects of the present invention are not limited to theaforementioned technical objects, and other technical objects, which arenot mentioned above, will be apparently appreciated by a person havingordinary skill in the art from the following description.

In accordance with an embodiment of the present invention, a method fortransmitting/receiving a signal in a wireless communication systemsupporting narrow-band (NB)-LTE, which is performed a terminal,including: receiving a narrow band synchronization signal from a basestation; acquiring time synchronization and frequency synchronizationwith the base station based on the narrow band synchronization signaland detecting an identifier of the base station; and receiving a narrowband broadcast channel from the base station based on the detectedidentifier of the base station, wherein the narrow band synchronizationsignal and the narrow band broadcast channel are received through anarrow band (NB), the narrow band has a system bandwidth of 180 kHz andincludes 12 subcarriers disposed at an interval of 15 kHz, the narrowband synchronization signal includes a narrow band primarysynchronization signal and a narrow band secondary synchronizationsignal, the narrow band primary synchronization signal and the narrowband secondary synchronization signal are transmitted in differentsubframes, and the narrow band broadcast channel is transmitted in afirst subframe of a radio frame.

Further, the narrow band primary synchronization signal may betransmitted in a 6^(th) subframe of the radio frame.

The narrow band synchronization signal and the narrow band broadcastchannel may not be transmitted in at least one resource in which areference signal (RS) is transmitted.

The narrow band synchronization signal and the narrow band broadcastchannel may not be transmitted in first three symbols of the firstsubframe and the sixth subframe.

Further, the first subframe and the sixth subframe may be subframeswhich are not configured as a multicast broadcast single frequencynetwork (MBSFN).

Transmission periods of the narrow band primary synchronization signaland the narrow band secondary synchronization signal may be set to bedifferent from each other.

The transmission period of the narrow band secondary synchronizationsignal may be set to 20 ms.

In addition, the narrow band synchronization signal and the narrow bandbroadcast channel may be transmitted through 11 orthogonal frequencydivision multiple access (OFDM) symbols.

Moreover, the narrow band secondary synchronization signal may betransmitted through 12 subcarriers.

Further, the method may further include verifying a frame structure typesupported by the base station based on at least one of the narrow bandsynchronization signal and the narrow band broadcast channel.

Moreover, the narrow band synchronization signal is generated by using aZadoff-Chu (ZC) sequence.

Further, the narrow band primary synchronization signal may be generatedbased on a first ZC sequence and a second ZC sequence having differentroot indexes.

In addition, the first ZC sequence and the second ZC sequence may bemapped to symbols to which the narrow band primary synchronizationsignal is transmitted, respectively.

Further, the frame structure type supported by the base station may bedistinguished according to the order in which the first ZC sequence andthe second ZC sequence are mapped to the symbols, respectively.

In addition, which the narrow band primary synchronization signal may begenerated based on a ZC sequence having a specific length and the ZCsequence having the specific length may be mapped to the symbols towhich the narrow band primary synchronization signal is transmitted.

In accordance with another embodiment of the present invention, aterminal for transmitting/receiving a signal in a wireless communicationsystem supporting narrow-band (NB)-LTE, including: a radio frequency(RF) unit for transmitting/receiving a wireless signal; and a processorfunctionally connected with the RF unit, wherein the processor controlsreceiving a narrow band synchronization signal from a base station,acquiring time synchronization and frequency synchronization with thebase station based on the narrow band synchronization signal anddetecting an identifier of the base station, and receiving a narrow bandbroadcast channel from the base station based on the detected identifierof the base station, the narrow band synchronization signal and thenarrow band broadcast channel are received through a narrow band (NB),the narrow band has a system bandwidth of 180 kHz and includes 12subcarriers disposed at an interval of 15 kHz, the narrow bandsynchronization signal includes a narrow band primary synchronizationsignal and a narrow band secondary synchronization signal, the narrowband primary synchronization signal and the narrow band secondarysynchronization signal are transmitted in different subframes, and thenarrow band broadcast channel is transmitted in a first subframe of aradio frame.

According to embodiments of the present invention, since a narrowbandsynchronization signal is transmitted in a subframe not configured as anMBSFN subframe, a collision with a PMCH transmitted through asynchronization signal in a narrowband system and an MBSFN subframe inan LTE system can be prevented.

Further, since a narrowband synchronization signal is configured not tobe mapped to an OFDM symbol in which a control channel such as a PDCCHis transmitted or an OFDM symbol in which a CRS is transmitted, animpact of a legacy system caused due to introduction of a narrowbandsynchronization signal can be minimized.

In addition, since the narrowband synchronization signal isdownlink-transmitted in a sixth subframe and a tenth subframe of a radioframe, the narrowband synchronization signal satisfies the mostcombinations/components among combinations/components that previouslydefine uplink transmission or downlink transmission for each subframe.

Since the narrowband synchronization signal is transmitted by usingremaining 11 OFDM symbols other than an OFDM symbol used fortransmitting a reference signal or a control channel, a terminal canmore accurately distinguish/decode the narrowband synchronizationsignal.

A frame structure type is defined to be distinguished through locationswhere the narrow synchronization signal and a narrowband broadcastchannel are transmitted to reduce complexity for decoding of a terminal.

Effects which can be obtained in the present invention are not limitedto the aforementioned effects and other unmentioned effects will beclearly understood by those skilled in the art from the followingdescription.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to help understanding of the present invention, theaccompanying drawings which are included as a part of the DetailedDescription provide embodiments of the present invention and describethe technical features of the present invention together with theDetailed Description.

FIG. 1 illustrates a structure of a radio frame in a wirelesscommunication system to which the present invention can be applied.

FIG. 2 is a diagram illustrating a resource grid for one downlink slotin the wireless communication system to which the present invention canbe applied.

FIG. 3 illustrates a structure of a downlink subframe in the wirelesscommunication system to which the present invention can be applied.

FIG. 4 illustrates a structure of an uplink subframe in the wirelesscommunication system to which the present invention can be applied.

FIG. 5 illustrates one example of a type in which PUCCH formats aremapped to a PUCCH area of an uplink physical resource block in thewireless communication system to which the present invention can beapplied.

FIG. 6 illustrates a structure of a CQI channel in the case of a normalCP in the wireless communication system to which the present inventioncan be applied.

FIG. 7 illustrates a structure of an ACK/NACK channel in the case of thenormal CP in the wireless communication system to which the presentinvention can be applied.

FIG. 8 illustrates one example of generating and transmitting 5 SC-FDMAsymbols during one slot in the wireless communication system to whichthe present invention can be applied.

FIG. 9 illustrates one example of a component carrier and carriermerging in the wireless communication system to which the presentinvention can be applied.

FIG. 10 illustrates one example of a subframe structure depending oncross carrier scheduling in the wireless communication system to whichthe present invention can be applied.

FIG. 11 illustrates one example of transmission channel processing of aUL-SCH in the wireless communication system to which the presentinvention can be applied.

FIG. 12 illustrates one example of a signal processing procedure of anuplink share channel which is a transport channel in the wirelesscommunication system to which the present invention can be applied.

FIG. 13 illustrates a reference signal pattern mapped to a downlinkresource block pair in the wireless communication system to which thepresent invention can be applied.

FIG. 14 illustrates an uplink subframe including a sounding referencesignal symbol in the wireless communication system to which the presentinvention can be applied.

FIG. 15 is a diagram illustrating one example in which a legacy PDCCH, alegacy PDSCH, and a legacy E-PDCCH are multiplexed.

FIG. 16 is a diagram illustrating classification of cells of a systemsupporting carrier merging.

FIG. 17 is a diagram illustrating a frame structure used for SStransmission in a system using a normal cyclic prefix (CP).

FIG. 18 is a diagram illustrating the frame structure used for the SStransmission in a system using an extended CP.

FIG. 19 is a diagram illustrating two sequences in a logic area areinterleaved and mapped in a physical area.

FIG. 20 is a diagram illustrating a frame structure in which an M-PSSand an M-SSS are mapped.

FIG. 21 is a diagram illustrating a method for generating an M-PSSaccording to an embodiment of the present invention.

FIG. 22 is a diagram illustrating a method for generating an M-SSSaccording to an embodiment of the present invention.

FIG. 23 illustrates one example of a method for implementing an M-PSS towhich a method proposed by the present specification can be applied.

FIG. 24 is a diagram illustrating how uplink numerology is stretched ina time domain.

FIG. 25 is a diagram illustrating one example of time units for uplinkof NB-LTE based on a 2.5 kHz subcarrier spacing.

FIG. 26 illustrates one example of an operation system of an NB LTEsystem to which a method proposed by the present specification can beapplied.

FIG. 27 illustrates one example of an NB-frame structure for a 15 kHzsubcarrier spacing to which a method proposed by the presentspecification can be applied.

FIG. 28 illustrates one example of an NB-frame structure for a 3.75 kHzsubcarrier spacing to which a method proposed by the presentspecification can be applied.

FIG. 29 illustrates one example of an NB subframe structure for a 3.75kHz subcarrier spacing to which a method proposed by the presentspecification can be applied.

FIG. 30 is a diagram illustrating one example of narrow bandsynchronization signal and narrow band broadcast channel configurationshaving the same location in a radio frame proposed by the presentspecification.

FIG. 31 is a diagram illustrating another example of the narrow bandsynchronization signal and narrow band broadcast channel configurationshaving the same location in the radio frame proposed by the presentspecification.

FIG. 32 is a diagram illustrating yet another example of the narrow bandsynchronization signal and narrow band broadcast channel configurationshaving the same location in the radio frame proposed by the presentspecification.

FIG. 33 is a diagram illustrating still yet another example of thenarrow band synchronization signal and narrow band broadcast channelconfigurations having the same location in the radio frame proposed bythe present specification.

FIG. 34 is a diagram illustrating still yet another example of thenarrow band synchronization signal and narrow band broadcast channelconfigurations having the same location in the radio frame proposed bythe present specification.

FIG. 35 illustrates one example of an M-PSS transmission structure towhich a method proposed by the present specification can be applied.

FIG. 36 is a diagram illustrating correlation characteristics dependingon various cover sequence patterns.

FIG. 37 illustrates one example of an SSS transmission structure towhich the method proposed by the present specification can be applied.

FIG. 38 illustrates one example of a method for transmitting an M-PSS byusing different sequences for each frame structure type proposed by thepresent specification.

FIG. 39 illustrates another example of the method for transmitting anM-PSS by using different sequences for each frame structure typeproposed by the present specification.

FIG. 40 is a diagram illustrating one example of narrow bandsynchronization signal and narrow band broadcast channel configurationshaving different locations in a radio frame proposed by the presentspecification.

FIG. 41 is a diagram illustrating another example of the narrow bandsynchronization signal and narrow band broadcast channel configurationshaving different locations in the radio frame proposed by the presentspecification.

FIG. 42 is a diagram illustrating yet another example of the narrow bandsynchronization signal and narrow band broadcast channel configurationshaving different locations in the radio frame proposed by the presentspecification.

FIG. 43 is a diagram illustrating still yet another example of thenarrow band synchronization signal and narrow band broadcast channelconfigurations having different locations in the radio frame proposed bythe present specification.

FIG. 44 is a flowchart illustrating one example of a method fortransmitting a narrow band synchronization signal and a narrow bandsynchronization signal by considering a frame structure type proposed bythe present specification.

FIG. 45 is a diagram illustrating one example of an internal blockdiagram of a wireless communication apparatus to which the methodsproposed by the present specification can be applied.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings. Adetailed description to be disclosed hereinbelow together with theaccompanying drawing is to describe embodiments of the present inventionand not to describe a unique embodiment for carrying out the presentinvention. The detailed description below includes details in order toprovide a complete understanding. However, those skilled in the art knowthat the present invention can be carried out without the details.

In some cases, in order to prevent a concept of the present inventionfrom being ambiguous, known structures and devices may be omitted or maybe illustrated in a block diagram format based on core function of eachstructure and device.

In the specification, a base station means a terminal node of a networkdirectly performing communication with a terminal. In the presentdocument, specific operations described to be performed by the basestation may be performed by an upper node of the base station in somecases. That is, it is apparent that in the network constituted bymultiple network nodes including the base station, various operationsperformed for communication with the terminal may be performed by thebase station or other network nodes other than the base station. A basestation (BS) may be generally substituted with terms such as a fixedstation, Node B, evolved-NodeB (eNB), a base transceiver system (BTS),an access point (AP), and the like. Further, a ‘terminal’ may be fixedor movable and be substituted with terms such as user equipment (UE), amobile station (MS), a user terminal (UT), a mobile subscriber station(MSS), a subscriber station (SS), an advanced mobile station (AMS), awireless terminal (WT), a Machine-Type Communication (MTC) device, aMachine-to-Machine (M2M) device, a Device-to-Device (D2D) device, andthe like.

Hereinafter, a downlink means communication from the base station to theterminal and an uplink means communication from the terminal to the basestation. In the downlink, a transmitter may be a part of the basestation and a receiver may be a part of the terminal. In the uplink, thetransmitter may be a part of the terminal and the receiver may be a partof the base station.

Specific terms used in the following description are provided to helpappreciating the present invention and the use of the specific terms maybe modified into other forms within the scope without departing from thetechnical spirit of the present invention.

The following technology may be used in various wireless access systems,such as code division multiple access (CDMA), frequency divisionmultiple access (FDMA), time division multiple access (TDMA), orthogonalfrequency division multiple access (OFDMA), single carrier-FDMA(SC-FDMA), non-orthogonal multiple access (NOMA), and the like. The CDMAmay be implemented by radio technology universal terrestrial radioaccess (UTRA) or CDMA2000. The TDMA may be implemented by radiotechnology such as Global System for Mobile communications (GSM)/GeneralPacket Radio Service (GPRS)/Enhanced Data Rates for GSM Evolution(EDGE). The OFDMA may be implemented as radio technology such as IEEE802.11(Wi-Fi), IEEE 802.16(WiMAX), IEEE 802-20, E-UTRA (Evolved UTRA),and the like. The UTRA is a part of a universal mobile telecommunicationsystem (UMTS). 3rd generation partnership project (3GPP) long termevolution (LTE) as a part of an evolved UMTS (E-UMTS) using evolved-UMTSterrestrial radio access (E-UTRA) adopts the OFDMA in a downlink and theSC-FDMA in an uplink. LTE-advanced (A) is an evolution of the 3GPP LTE.

The embodiments of the present invention may be based on standarddocuments disclosed in at least one of IEEE 802, 3GPP, and 3GPP2 whichare the wireless access systems. That is, steps or parts which are notdescribed to definitely show the technical spirit of the presentinvention among the embodiments of the present invention may be based onthe documents. Further, all terms disclosed in the document may bedescribed by the standard document.

3GPP LTE/LTE-A is primarily described for clear description, buttechnical features of the present invention are not limited thereto.

General System

FIG. 1 illustrates a structure a radio frame in a wireless communicationsystem to which the present invention can be applied.

In 3GPP LTE/LTE-A, radio frame structure type 1 may be applied tofrequency division duplex (FDD) and radio frame structure type 2 may beapplied to time division duplex (TDD) are supported.

FIG. 1(a) exemplifies radio frame structure type 1. The radio frame isconstituted by 10 subframes. One subframe is constituted by 2 slots in atime domain. A time required to transmit one subframe is referred to asa transmissions time interval (TTI). For example, the length of onesubframe may be 1 ms and the length of one slot may be 0.5 ms.

One slot includes a plurality of orthogonal frequency divisionmultiplexing (OFDM) symbols in the time domain and includes multipleresource blocks (RBs) in a frequency domain. In 3GPP LTE, since OFDMA isused in downlink, the OFDM symbol is used to express one symbol period.The OFDM symbol may be one SC-FDMA symbol or symbol period. The resourceblock is a resource allocation wise and includes a plurality ofconsecutive subcarriers in one slot.

FIG. 1(b) illustrates frame structure type 2. Radio frame type 2 isconstituted by 2 half frames, each half frame is constituted by 5subframes, a downlink pilot time slot (DwPTS), a guard period (GP), andan uplink pilot time slot (UpPTS), and one subframe among them isconstituted by 2 slots. The DwPTS is used for initial cell discovery,synchronization, or channel estimation in a terminal. The UpPTS is usedfor channel estimation in a base station and to match uplinktransmission synchronization of the terminal. The guard period is aperiod for removing interference which occurs in uplink due tomulti-path delay of a downlink signal between the uplink and thedownlink.

In frame structure type 2 of a TDD system, an uplink-downlinkconfiguration is a rule indicating whether the uplink and the downlinkare allocated (alternatively, reserved) with respect to all subframes.Table 1 shows he uplink-downlink configuration.

TABLE 1 Downlink- to- Uplink Uplink- Switch- Downlink point Subframenumber configuration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U DS U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms  DS U U U D D D D D 4 10 ms  D S U U D D D D D D 5 10 ms  D S U D D D D DD D 6 5 ms D S U U U D S U U D

Referring to Table 1, for each sub frame of the radio frame, ‘D’represents a subframe for downlink transmission, ‘U’ represents asubframe for uplink transmission, and ‘S’ represents a special subframeconstituted by three fields such as the DwPTS, the GP, and the UpPTS.The uplink-downlink configuration may be divided into 7 configurationsand the positions and/or the numbers of the downlink subframe, thespecial subframe, and the uplink subframe may vary for eachconfiguration.

A time when the downlink is switched to the uplink or a time when theuplink is switched to the downlink is referred to as a switching point.Switch-point periodicity means a period in which an aspect of the uplinksubframe and the downlink subframe are switched is similarly repeatedand both 5 ms or 10 ms are supported. When the period of thedownlink-uplink switching point is 5 ms, the special subframe S ispresent for each half-frame and when the period of the downlink-uplinkswitching point is 5 ms, the special subframe S is present only in afirst half-frame.

In all configurations, subframes #0 and #5 and the DwPTS are intervalsonly the downlink transmission. The UpPTS and a subframe justsubsequently to the subframe are continuously intervals for the uplinktransmission.

The uplink-downlink configuration may be known by both the base stationand the terminal as system information. The base station transmits onlyan index of configuration information whenever the uplink-downlinkconfiguration information is changed to announce a change of anuplink-downlink allocation state of the radio frame to the terminal.Further, the configuration information as a kind of downlink controlinformation may be transmitted through a physical downlink controlchannel (PDCCH) similarly to other scheduling information and may becommonly transmitted to all terminals in a cell through a broadcastchannel as broadcasting information.

The structure of the radio frame is just one example and the numbersubcarriers included in the radio frame or the number of slots includedin the subframe and the number of OFDM symbols included in the slot maybe variously changed.

FIG. 2 is a diagram illustrating a resource grid for one downlink slotin the wireless communication system to which the present invention canbe applied.

Referring to FIG. 2, one downlink slot includes the plurality of OFDMsymbols in the time domain. Herein, it is exemplarily described that onedownlink slot includes 7 OFDM symbols and one resource block includes 12subcarriers in the frequency domain, but the present invention is notlimited thereto.

Each element on the resource grid is referred to as a resource elementand one resource block includes 12×7 resource elements. The number ofresource blocks included in the downlink slot, NDL is subordinated to adownlink transmission bandwidth.

A structure of the uplink slot may be the same as that of the downlinkslot.

FIG. 3 illustrates a structure of a downlink subframe in the wirelesscommunication system to which the present invention can be applied.

Referring to FIG. 3, a maximum of three fore OFDM symbols in the firstslot of the sub frame is a control region to which control channels areallocated and residual OFDM symbols is a data region to which a physicaldownlink shared channel (PDSCH) is allocated. Examples of the downlinkcontrol channel used in the 3GPP LTE include a Physical Control FormatIndicator Channel (PCFICH), a Physical Downlink Control Channel (PDCCH),a Physical Hybrid-ARQ Indicator Channel (PHICH), and the like.

The PFCICH is transmitted in the first OFDM symbol of the subframe andtransports information on the number (that is, the size of the controlregion) of OFDM symbols used for transmitting the control channels inthe subframe. The PHICH which is a response channel to the uplinktransports an Acknowledgement (ACK)/Not-Acknowledgement (NACK) signalfor a hybrid automatic repeat request (HARQ). Control informationtransmitted through a PDCCH is referred to as downlink controlinformation (DCI). The downlink control information includes uplinkresource allocation information, downlink resource allocationinformation, or an uplink transmission (Tx) power control command for apredetermined terminal group.

The PDCCH may transport A resource allocation and transmission format(also referred to as a downlink grant) of a downlink shared channel(DL-SCH), resource allocation information (also referred to as an uplinkgrant) of an uplink shared channel (UL-SCH), paging information in apaging channel (PCH), system information in the DL-SCH, resourceallocation for an upper-layer control message such as a random accessresponse transmitted in the PDSCH, an aggregate of transmission powercontrol commands for individual terminals in the predetermined terminalgroup, a voice over IP (VoIP). A plurality of PDCCHs may be transmittedin the control region and the terminal may monitor the plurality ofPDCCHs. The PDCCH is constituted by one or an aggregate of a pluralityof continuous control channel elements (CCEs). The CCE is a logicalallocation wise used to provide a coding rate depending on a state of aradio channel to the PDCCH. The CCEs correspond to a plurality ofresource element groups. A format of the PDCCH and a bit number ofusable PDCCH are determined according to an association between thenumber of CCEs and the coding rate provided by the CCEs.

The base station determines the PDCCH format according to the DCI to betransmitted and attaches the control information to a cyclic redundancycheck (CRC) to the control information. The CRC is masked with a uniqueidentifier (referred to as a radio network temporary identifier (RNTI))according to an owner or a purpose of the PDCCH. In the case of a PDCCHfor a specific terminal, the unique identifier of the terminal, forexample, a cell-RNTI (C-RNTI) may be masked with the CRC. Alternatively,in the case of a PDCCH for the paging message, a paging indicationidentifier, for example, the CRC may be masked with a paging-RNTI(P-RNTI). In the case of a PDCCH for the system information, in moredetail, a system information block (SIB), the CRC may be masked with asystem information identifier, that is, a system information (SI)-RNTI.The CRC may be masked with a random access (RA)-RNTI in order toindicate the random access response which is a response to transmissionof a random access preamble.

FIG. 4 illustrates a structure of an uplink subframe in the wirelesscommunication system to which the present invention can be applied.

Referring to FIG. 4, the uplink subframe may be divided into the controlregion and the data region in a frequency domain. A physical uplinkcontrol channel (PUCCH) transporting uplink control information isallocated to the control region. A physical uplink shared channel(PUSCH) transporting user data is allocated to the data region. Oneterminal does not simultaneously transmit the PUCCH and the PUSCH inorder to maintain a single carrier characteristic.

A resource block (RB) pair in the subframe are allocated to the PUCCHfor one terminal. RBs included in the RB pair occupy differentsubcarriers in two slots, respectively. The RB pair allocated to thePUCCH frequency-hops in a slot boundary.

Physical Uplink Control Channel (PUCCH)

The uplink control information (UCI) transmitted through the PUCCH mayinclude a scheduling request (SR), HARQ ACK/NACK information, anddownlink channel measurement information.

The HARQ ACK/NACK information may be generated according to a downlinkdata packet on the PDSCH is successfully decoded. In the existingwireless communication system, 1 bit is transmitted as ACK/NACKinformation with respect to downlink single codeword transmission and 2bits are transmitted as the ACK/NACK information with respect todownlink 2-codeword transmission.

The channel measurement information which designates feedbackinformation associated with a multiple input multiple output (MIMO)technique may include a channel quality indicator (CQI), a precodingmatrix index (PMI), and a rank indicator (RI). The channel measurementinformation may also be collectively expressed as the CQI.

20 bits may be used per subframe for transmitting the CQI.

The PUCCH may be modulated by using binary phase shift keying (BPSK) andquadrature phase shift keying (QPSK) techniques. Control information ofa plurality of terminals may be transmitted through the PUCCH and whencode division multiplexing (CDM) is performed to distinguish signals ofthe respective terminals, a constant amplitude zero autocorrelation(CAZAC) sequence having a length of 12 is primary used. Since the CAZACsequence has a characteristic to maintain a predetermined amplitude inthe time domain and the frequency domain, the CAZAC sequence has aproperty suitable for increasing coverage by decreasing apeak-to-average power ratio (PAPR) or cubic metric (CM) of the terminal.Further, the ACK/NACK information for downlink data transmissionperformed through the PUCCH is covered by using an orthogonal sequenceor an orthogonal cover (OC).

Further, the control information transmitted on the PUCCH may bedistinguished by using a cyclically shifted sequence having differentcyclic shift (CS) values. The cyclically shifted sequence may begenerated by cyclically shifting a base sequence by a specific cyclicshift (CS) amount. The specific CS amount is indicated by the cyclicshift (CS) index. The number of usable cyclic shifts may vary dependingon delay spread of the channel. Various types of sequences may be usedas the base sequence the CAZAC sequence is one example of thecorresponding sequence.

Further, the amount of control information which the terminal maytransmit in one subframe may be determined according to the number (thatis, SC-FDMA symbols other an SC-FDMA symbol used for transmitting areference signal (RS) for coherent detection of the PUCCH) of SC-FDMAsymbols which are usable for transmitting the control information.

In the 3GPP LTE system, the PUCCH is defined as a total of 7 differentformats according to the transmitted control information, a modulationtechnique, the amount of control information, and the like and anattribute of the uplink control information (UCI) transmitted accordingto each PUCCH format may be summarized as shown in Table 2 given below.

TABLE 2 PUCCH Format Uplink Control Information(UCI) Format 1 SchedulingRequest(SR)(unmodulated waveform) Format 1a 1-bit HARQ ACK/NACKwith/without SR Format 1b 2-bit HARQ ACK/NACK with/without SR Format 2CQI (20 coded bits) Format 2 CQI and 1- or 2-bit HARQ ACK/NACK (20 bits)for extended CP only Format 2a CQI and 1-bit HARQ ACK/NACK (20 + 1 codedbits) Format 2b CQI and 2-bit HARQ ACK/NACK (20 + 2 coded bits)

PUCCH format 1 is used for transmitting only the SR. A waveform which isnot modulated is adopted in the case of transmitting only the SR andthis will be described below in detail.

PUCCH format 1 a or 1 b is used for transmitting the HARQ ACK/NACK.PUCCH format 1a or 1 b may be used when only the HARQ ACK/NACK istransmitted in a predetermined subframe. Alternatively, the HARQACK/NACK and the SR may be transmitted in the same subframe by usingPUCCH format 1a or 1b.

PUCCH format 2 is used for transmitting the CQI and PUCCH format 2a or2b is used for transmitting the CQI and the HARQ ACK/NACK.

In the case of an extended CP, PUCCH format 2 may be transmitted fortransmitting the CQI and the HARQ ACK/NACK.

FIG. 5 illustrates one example of a type in which PUCCH formats aremapped to a PUCCH region of an uplink physical resource block in thewireless communication system to which the present invention can beapplied.

In FIG. 5, N_(RB) ^(UL) represents the number of resource blocks in theuplink and 0, 1, . . . , N_(RB) ^(UL)−1 mean numbers of physicalresource blocks. Basically, the PUCCH is mapped to both edges of anuplink frequency block. As illustrated in FIG. 5, PUCCH format 2/2a/2bis mapped to a PUCCH region expressed as m=0, 1 and this may beexpressed in such a manner that PUCCH format 2/2a/2b is mapped toresource blocks positioned at a band edge. Further, both PUCCH format2/2a/2b and PUCCH format 1/1a/1b may be mixedly mapped to a PUCCH regionexpressed as m=2. Next, PUCCH format 1/1a/1b may be mapped to a PUCCHregion expressed as m=3, 4, and 5. The number (N_(RB) ⁽²⁾) of PUCCH RBswhich are usable by PUCCH format 2/2a/2b may be indicated to terminalsin the cell by broadcasting signaling.

PUCCH format 2/2a/2b is described. PUCCH format 2/2a/2b is a controlchannel for transmitting channel measurement feedback (CQI, PMI, andRI).

A reporting period of the channel measurement feedbacks (hereinafter,collectively expressed as CQI information) and a frequency wise(alternatively, a frequency resolution) to be measured may be controlledby the base station. In the time domain, periodic and aperiodic CQIreporting may be supported. PUCCH format 2 may be used for only theperiodic reporting and the PUSCH may be used for aperiodic reporting. Inthe case of the aperiodic reporting, the base station may instruct theterminal to transmit a scheduling resource loaded with individual CQIreporting for the uplink data transmission.

FIG. 6 illustrates a structure of a CQI channel in the case of a generalCP in the wireless communication system to which the present inventioncan be applied.

In SC-FDMA symbols 0 to 6 of one slot, SC-FDMA symbols 1 and 5 (secondand sixth symbols) may be used for transmitting a demodulation referencesignal and the CQI information may be transmitted in the residualSC-FDMA symbols. Meanwhile, in the case of the extended CP, one SC-FDMAsymbol (SC-FDMA symbol 3) is used for transmitting the DMRS.

In PUCCH format 2/2a/2b, modulation by the CAZAC sequence is supportedand the CAZAC sequence having the length of 12 is multiplied by aQPSK-modulated symbol. The cyclic shift (CS) of the sequence is changedbetween the symbol and the slot. The orthogonal covering is used withrespect to the DMRS.

The reference signal (DMRS) is loaded on two SC-FDMA symbols separatedfrom each other by 3 SC-FDMA symbols among 7 SC-FDMA symbols included inone slot and the CQI information is loaded on 5 residual SC-FDMAsymbols. Two RSs are used in one slot in order to support a high-speedterminal. Further, the respective terminals are distinguished by usingthe CS sequence. CQI information symbols are modulated and transferredto all SC-FDMA symbols and the SC-FDMA symbol is constituted by onesequence. That is, the terminal modulates and transmits the CQI to eachsequence.

The number of symbols which may be transmitted to one TTI is 10 andmodulation of the CQI information is determined up to QPSK. When QPSKmapping is used for the SC-FDMA symbol, since a CQI value of 2 bits maybe loaded, a CQI value of 10 bits may be loaded on one slot. Therefore,a CQI value of a maximum of 20 bits may be loaded on one subframe. Afrequency domain spread code is used for spreading the CQI informationin the frequency domain.

The CAZAC sequence (for example, ZC sequence) having the length of 12may be used as the frequency domain spread code. CAZAC sequences havingdifferent CS values may be applied to the respective control channels tobe distinguished from each other. IFFT is performed with respect to theCQI information in which the frequency domain is spread.

12 different terminals may be orthogonally multiplexed on the same PUCCHRB by a cyclic shift having 12 equivalent intervals. In the case of ageneral CP, a DMRS sequence on SC-FDMA symbol 1 and 5 (on SC-FDMA symbol3 in the case of the extended CP) is similar to a CQI signal sequence onthe frequency domain, but the modulation of the CQI information is notadopted.

The terminal may be semi-statically configured by upper-layer signalingso as to periodically report different CQI, PMI, and RI types on PUCCHresources indicated as PUCCH resource indexes (n_(PUCCH)^((1,{tilde over (p)})), n_(PUCCH) ^((2,{tilde over (p)})), andn_(PUCCH) ^((3,{tilde over (p)}))). Herein, the PUCCH resource index(n_(PUCCH) ^((2,{tilde over (p)}))) is information indicating the PUCCHregion used for PUCCH format 2/2a/2b and a CS value to be used.

PUCCH Channel Structure

PUCCH formats 1a and 1b are described.

In PUCCH format 1a and 1b, the CAZAC sequence having the length of 12 ismultiplied by a symbol modulated by using a BPSK or QPSK modulationscheme. For example, a result acquired by multiplying a modulated symbold (0) by a CAZAC sequence r (n) (n=0, 1, 2, . . . , N−1) having a lengthof N becomes y(0), y(1), y(2), . . . , y(N−1). y(0), . . . , y(N−1)symbols may be designated as a block of symbols. The modulated symbol ismultiplied by the CAZAC sequence and thereafter, the block-wise spreadusing the orthogonal sequence is adopted.

A Hadamard sequence having a length of 4 is used with respect to generalACK/NACK information and a discrete Fourier transform (DFT) sequencehaving a length of 3 is used with respect to the ACK/NACK informationand the reference signal.

The Hadamard sequence having the length of 2 is used with respect to thereference signal in the case of the extended CP.

FIG. 7 illustrates a structure of an ACK/NACK channel in the case of ageneral CP in the wireless communication system to which the presentinvention can be applied.

In FIG. 7, a PUCCH channel structure for transmitting the HARQ ACK/NACKwithout the CQI is exemplarily illustrated.

The reference signal (DMRS) is loaded on three consecutive SC-FDMAsymbols in a middle part among 7 SC-FDMA symbols and the ACK/NACK signalis loaded on 4 residual SC-FDMA symbols.

Meanwhile, in the case of the extended CP, the RS may be loaded on twoconsecutive symbols in the middle part. The number of and the positionsof symbols used in the RS may vary depending on the control channel andthe numbers and the positions of symbols used in the ACK/NACK signalassociated with the positions of symbols used in the RS may alsocorrespondingly vary depending on the control channel.

Acknowledgment response information (not scrambled status) of 1 bit and2 bits may be expressed as one HARQ ACK/NACK modulated symbol by usingthe BPSK and QPSK modulation techniques, respectively. A positiveacknowledgement response (ACK) may be encoded as ‘1’ and a negativeacknowledgment response (NACK) may be encoded as ‘0’.

When a control signal is transmitted in an allocated band, 2-dimensional(D) spread is adopted in order to increase a multiplexing capacity. Thatis, frequency domain spread and time domain spread are simultaneouslyadopted in order to increase the number of terminals or control channelswhich may be multiplexed.

A frequency domain sequence is used as the base sequence in order tospread the ACK/NACK signal in the frequency domain. A Zadoff-Chu (ZC)sequence which is one of the CAZAC sequences may be used as thefrequency domain sequence. For example, different CSs are applied to theZC sequence which is the base sequence, and as a result, multiplexingdifferent terminals or different control channels may be applied. Thenumber of CS resources supported in an SC-FDMA symbol for PUCCH RBs forHARQ ACK/NACK transmission is set by a cell-specific upper-layersignaling parameter (Δ_(shift) ^(PUCCH)).

The ACK/NACK signal which is frequency-domain spread is spread in thetime domain by using an orthogonal spreading code. As the orthogonalspreading code, a Walsh-Hadamard sequence or DFT sequence may be used.For example, the ACK/NACK signal may be spread by using an orthogonalsequence (w0, w1, w2, and w3) having the length of 4 with respect to 4symbols. Further, the RS is also spread through an orthogonal sequencehaving the length of 3 or 2. This is referred to as orthogonal covering(OC).

Multiple terminals may be multiplexed by a code division multiplexing(CDM) scheme by using the CS resources in the frequency domain and theOC resources in the time domain described above. That is, ACK/NACKinformation and RSs of a lot of terminals may be multiplexed on the samePUCCH RB.

In respect to the time-domain spread CDM, the number of spreading codessupported with respect to the ACK/NACK information is limited by thenumber of RS symbols. That is, since the number of RS transmittingSC-FDMA symbols is smaller than that of ACK/NACK informationtransmitting SC-FDMA symbols, the multiplexing capacity of the RS issmaller than that of the ACK/NACK information.

For example, in the case of the general CP, the ACK/NACK information maybe transmitted in four symbols and not 4 but 3 orthogonal spreadingcodes are used for the ACK/NACK information and the reason is that thenumber of RS transmitting symbols is limited to 3 to use only 3orthogonal spreading codes for the RS.

In the case of the subframe of the general CP, when 3 symbols are usedfor transmitting the RS and 4 symbols are used for transmitting theACK/NACK information in one slot, for example, if 6 CSs in the frequencydomain and 3 orthogonal cover (OC) resources may be used, HARQacknowledgement responses from a total of 18 different terminals may bemultiplexed in one PUCCH RB. In the case of the subframe of the extendedCP, when 2 symbols are used for transmitting the RS and 4 symbols areused for transmitting the ACK/NACK information in one slot, for example,if 6 CSs in the frequency domain and 2 orthogonal cover (OC) resourcesmay be used, the HARQ acknowledgement responses from a total of 12different terminals may be multiplexed in one PUCCH RB.

Next, PUCCH format 1 is described. The scheduling request (SR) istransmitted by a scheme in which the terminal requests scheduling ordoes not request the scheduling. An SR channel reuses an ACK/NACKchannel structure in PUCCH format 1a/1b and is configured by an on-offkeying (OOK) scheme based on an ACK/NACK channel design. In the SRchannel, the reference signal is not transmitted. Therefore, in the caseof the general CP, a sequence having a length of 7 is used and in thecase of the extended CP, a sequence having a length of 6 is used.Different cyclic shifts (CSs) or orthogonal covers (OCs) may beallocated to the SR and the ACK/NACK. That is, the terminal transmitsthe HARQ ACK/NACK through a resource allocated for the SR in order totransmit a positive SR. The terminal transmits the HARQ ACK/NACK througha resource allocated for the ACK/NACK in order to transmit a negativeSR.

Next, an enhanced-PUCCH (e-PUCCH) format is described. An e-PUCCH maycorrespond to PUCCH format 3 of an LTE-A system. A block spreadingtechnique may be applied to ACK/NACK transmission using PUCCH format 3.

The block spreading technique is a scheme that modulates transmission ofthe control signal by using the SC-FDMA scheme unlike the existing PUCCHformat 1 series or 2 series. As illustrated in FIG. 8, a symbol sequencemay be spread and transmitted on the time domain by using an orthogonalcover code (OCC). The control signals of the plurality of terminals maybe multiplexed on the same RB by using the OCC. In the case of PUCCHformat 2 described above, one symbol sequence is transmitted throughoutthe time domain and the control signals of the plurality of terminalsare multiplexed by using the cyclic shift (CS) of the CAZAC sequence,while in the case of a block spreading based on PUCCH format (forexample, PUCCH format 3), one symbol sequence is transmitted throughoutthe frequency domain and the control signals of the plurality ofterminals are multiplexed by using the time domain spreading using theOCC.

FIG. 8 illustrates one example of generating and transmitting 5 SC-FDMAsymbols during one slot in the wireless communication system to whichthe present invention can be applied.

In FIG. 8, an example of generating and transmitting 5 SC-FDMA symbols(that is, data part) by using an OCC having the length of 5(alternatively, SF=5) in one symbol sequence during one slot. In thiscase, two RS symbols may be used during one slot.

In the example of FIG. 8, the RS symbol may be generated from a CAZACsequence to which a specific cyclic shift value is applied andtransmitted in a type in which a predetermined OCC is applied(alternatively, multiplied) throughout a plurality of RS symbols.Further, in the example of FIG. 8, when it is assumed that 12 modulatedsymbols are used for each OFDM symbol (alternatively, SC-FDMA symbol)and the respective modulated symbols are generated by QPSK, the maximumbit number which may be transmitted in one slot becomes 24 bits (=12×2).Accordingly, the bit number which is transmittable by two slots becomesa total of 48 bits. When a PUCCH channel structure of the blockspreading scheme is used, control information having an extended sizemay be transmitted as compared with the existing PUCCH format 1 seriesand 2 series.

General Carrier Aggregation

A communication environment considered in embodiments of the presentinvention includes multi-carrier supporting environments. That is, amulti-carrier system or a carrier aggregation system used in the presentinvention means a system that aggregates and uses one or more componentcarriers (CCs) having a smaller bandwidth smaller than a target band atthe time of configuring a target wideband in order to support awideband.

In the present invention, multi-carriers mean aggregation of(alternatively, carrier aggregation) of carriers and in this case, theaggregation of the carriers means both aggregation between continuouscarriers and aggregation between non-contiguous carriers. Further, thenumber of component carriers aggregated between the downlink and theuplink may be differently set. A case in which the number of downlinkcomponent carriers (hereinafter, referred to as ‘DL CC’) and the numberof uplink component carriers (hereinafter, referred to as ‘UL CC’) arethe same as each other is referred to as symmetric aggregation and acase in which the number of downlink component carriers and the numberof uplink component carriers are different from each other is referredto as asymmetric aggregation. The carrier aggregation may be usedmixedly with a term such as the carrier aggregation, the bandwidthaggregation, spectrum aggregation, or the like.

The carrier aggregation configured by combining two or more componentcarriers aims at supporting up to a bandwidth of 100 MHz in the LTE-Asystem. When one or more carriers having the bandwidth than the targetband are combined, the bandwidth of the carriers to be combined may belimited to a bandwidth used in the existing system in order to maintainbackward compatibility with the existing IMT system. For example, theexisting 3GPP LTE system supports bandwidths of 1.4, 3, 5, 10, 15, and20 MHz and a 3GPP LTE-advanced system (that is, LTE-A) may be configuredto support a bandwidth larger than 20 MHz by using on the bandwidth forcompatibility with the existing system. Further, the carrier aggregationsystem used in the preset invention may be configured to support thecarrier aggregation by defining a new bandwidth regardless of thebandwidth used in the existing system.

The LTE-A system uses a concept of the cell in order to manage a radioresource.

The carrier aggregation environment may be called a multi-cellenvironment. The cell is defined as a combination of a pair of adownlink resource (DL CC) and an uplink resource (UL CC), but the uplinkresource is not required. Therefore, the cell may be constituted by onlythe downlink resource or both the downlink resource and the uplinkresource. When a specific terminal has only one configured serving cell,the cell may have one DL CC and one UL CC, but when the specificterminal has two or more configured serving cells, the cell has DL CCsas many as the cells and the number of UL CCs may be equal to or smallerthan the number of DL CCs.

Alternatively, contrary to this, the DL CC and the UL CC may beconfigured. That is, when the specific terminal has multiple configuredserving cells, a carrier aggregation environment having UL CCs more thanDL CCs may also be supported. That is, the carrier aggregation may beappreciated as aggregation of two or more cells having different carrierfrequencies (center frequencies). Herein, the described ‘cell’ needs tobe distinguished from a cell as an area covered by the base stationwhich is generally used.

The cell used in the LTE-A system includes a primary cell (PCell) and asecondary cell (SCell. The P cell and the S cell may be used as theserving cell. In a terminal which is in an RRC_CONNECTED state, but doesnot have the configured carrier aggregation or does not support thecarrier aggregation, only one serving constituted by only the P cell ispresent. On the contrary, in a terminal which is in the RRC_CONNECTEDstate and has the configured carrier aggregation, one or more servingcells may be present and the P cell and one or more S cells are includedin all serving cells.

The serving cell (P cell and S cell) may be configured through an RRCparameter. PhysCellId as a physical layer identifier of the cell hasinteger values of 0 to 503. SCellIndex as a short identifier used toidentify the S cell has integer values of 1 to 7. ServCellIndex as ashort identifier used to identify the serving cell (P cell or S cell)has the integer values of 0 to 7. The value of 0 is applied to the Pcell and SCellIndex is previously granted for application to the S cell.That is, a cell having a smallest cell ID (alternatively, cell index) inServCellIndex becomes the P cell.

The P cell means a cell that operates on a primary frequency(alternatively, primary CC). The terminal may be used to perform aninitial connection establishment process or a connectionre-establishment process and may be designated as a cell indicatedduring a handover process. Further, the P cell means a cell whichbecomes the center of control associated communication among servingcells configured in the carrier aggregation environment. That is, theterminal may be allocated with and transmit the PUCCH only in the P cellthereof and use only the P cell to acquire the system information orchange a monitoring procedure. An evolved universal terrestrial radioaccess (E-UTRAN) may change only the P cell for the handover procedureto the terminal supporting the carrier aggregation environment by usingan RRC connection reconfiguration message (RRCConnectionReconfigutaion)message of an upper layer including mobile control information(mobilityControlInfo).

The S cell means a cell that operates on a secondary frequency(alternatively, secondary CC). Only one P cell may be allocated to aspecific terminal and one or more S cells may be allocated to thespecific terminal. The S cell may be configured after RRC connectionestablishment is achieved and used for providing an additional radioresource. The PUCCH is not present in residual cells other than the Pcell, that is, the S cells among the serving cells configured in thecarrier aggregation environment. The E-UTRAN may provide all systeminformation associated with a related cell which is in an RRC_CONNECTEDstate through a dedicated signal at the time of adding the S cells tothe terminal that supports the carrier aggregation environment. A changeof the system information may be controlled by releasing and adding therelated S cell and in this case, the RRC connection reconfiguration(RRCConnectionReconfigutaion) message of the upper layer may be used.The E-UTRAN may perform having different parameters for each terminalrather than broadcasting in the related S cell.

After an initial security activation process starts, the E-UTRAN addsthe S cells to the P cell initially configured during the connectionestablishment process to configure a network including one or more Scells. In the carrier aggregation environment, the P cell and the S cellmay operate as the respective component carriers. In an embodimentdescribed below, the primary component carrier (PCC) may be used as thesame meaning as the P cell and the secondary component carrier (SCC) maybe used as the same meaning as the S cell.

FIG. 9 illustrates examples of a component carrier and carrieraggregation in the wireless communication system to which the presentinvention can be applied.

FIG. 9a illustrates a single carrier structure used in an LTE system.The component carrier includes the DL CC and the UL CC. One componentcarrier may have a frequency range of 20 MHz.

FIG. 9b illustrates a carrier aggregation structure used in the LTEsystem. In the case of FIG. 9b , a case is illustrated, in which threecomponent carriers having a frequency magnitude of 20 MHz are combined.Each of three DL CCs and three UL CCs is provided, but the number of DLCCs and the number of UL CCs are not limited. In the case of carrieraggregation, the terminal may simultaneously monitor three CCs, andreceive downlink signal/data and transmit uplink signal/data.

When N DL CCs are managed in a specific cell, the network may allocate M(M≤N) DL CCs to the terminal. In this case, the terminal may monitoronly M limited DL CCs and receive the DL signal. Further, the networkgives L (L≤M≤N) DL CCs to allocate a primary DL CC to the terminal andin this case, UE needs to particularly monitor L DL CCs. Such a schememay be similarly applied even to uplink transmission.

A linkage between a carrier frequency (alternatively, DL CC) of thedownlink resource and a carrier frequency (alternatively, UL CC) of theuplink resource may be indicated by an upper-layer message such as theRRC message or the system information. For example, a combination of theDL resource and the UL resource may be configured by a linkage definedby system information block type 2 (SIB2). In detail, the linkage maymean a mapping relationship between the DL CC in which the PDCCHtransporting a UL grant and a UL CC using the UL grant and mean amapping relationship between the DL CC (alternatively, UL CC) in whichdata for the HARQ is transmitted and the UL CC (alternatively, DL CC) inwhich the HARQ ACK/NACK signal is transmitted.

Cross Carrier Scheduling

In the carrier aggregation system, in terms of scheduling for thecarrier or the serving cell, two types of a self-scheduling method and across carrier scheduling method are provided. The cross carrierscheduling may be called cross component carrier scheduling or crosscell scheduling.

The cross carrier scheduling means transmitting the PDCCH (DL grant) andthe PDSCH to different respective DL CCs or transmitting the PUSCHtransmitted according to the PDCCH (UL grant) transmitted in the DL CCthrough other UL CC other than a UL CC linked with the DL CC receivingthe UL grant.

Whether to perform the cross carrier scheduling may be UE-specificallyactivated or deactivated and semi-statically known for each terminalthrough the upper-layer signaling (for example, RRC signaling).

When the cross carrier scheduling is activated, a carrier indicatorfield (CIF) indicating through which DL/UL CC the PDSCH/PUSCH thePDSCH/PUSCH indicated by the corresponding PDCCH is transmitted isrequired. For example, the PDCCH may allocate the PDSCH resource or thePUSCH resource to one of multiple component carriers by using the CIF.That is, the CIF is set when the PDSCH or PUSCH resource is allocated toone of DL/UL CCs in which the PDCCH on the DL CC is multiply aggregated.In this case, a DCI format of LTE-A Release-8 may extend according tothe CIF. In this case, the set CIF may be fixed to a 3-bit field and theposition of the set CIF may be fixed regardless of the size of the DCIformat. Further, a PDCCH structure (the same coding and the same CCEbased resource mapping) of the LTE-A Release-8 may be reused.

On the contrary, when the PDCCH on the DL CC allocates the PDSCHresource on the same DL CC or allocates the PUSCH resource on a UL CCwhich is singly linked, the CIF is not set. In this case, the same PDCCHstructure (the same coding and the same CCE based resource mapping) andDCI format as the LTE-A Release-8 may be used.

When the cross carrier scheduling is possible, the terminal needs tomonitor PDCCHs for a plurality of DCIs in a control region of amonitoring CC according to a transmission mode and/or a bandwidth foreach CC. Therefore, a configuration and PDCCH monitoring of a searchspace which may support monitoring the PDCCHs for the plurality of DCIsare required.

In the carrier aggregation system, a terminal DL CC aggregate representsan aggregate of DL CCs in which the terminal is scheduled to receive thePDSCH and a terminal UL CC aggregate represents an aggregate of UL CCsin which the terminal is scheduled to transmit the PUSCH. Further, aPDCCH monitoring set represents a set of one or more DL CCs that performthe PDCCH monitoring. The PDCCH monitoring set may be the same as theterminal DL CC set or a subset of the terminal DL CC set. The PDCCHmonitoring set may include at least any one of DL CCs in the terminal DLCC set. Alternatively, the PDCCH monitoring set may be definedseparately regardless of the terminal DL CC set. The DL CCs included inthe PDCCH monitoring set may be configured in such a manner thatself-scheduling for the linked UL CC is continuously available. Theterminal DL CC set, the terminal UL CC set, and the PDCCH monitoring setmay be configured UE-specifically, UE group-specifically, orcell-specifically.

When the cross carrier scheduling is deactivated, the deactivation ofthe cross carrier scheduling means that the PDCCH monitoring setcontinuously means the terminal DL CC set and in this case, anindication such as separate signaling for the PDCCH monitoring set isnot required. However, when the cross carrier scheduling is activated,the PDCCH monitoring set is preferably defined in the terminal DL CCset. That is, the base station transmits the PDCCH through only thePDCCH monitoring set in order to schedule the PDSCH or PUSCH for theterminal.

FIG. 10 illustrates one example of a subframe structure depending oncross carrier scheduling in the wireless communication system to whichthe present invention can be applied.

Referring to FIG. 10, a case is illustrated, in which three DL CCs areassociated with a DL subframe for an LTE-A terminal and DL CC ‘A’ isconfigured as a PDCCH monitoring DL CC. When the CIF is not used, eachDL CC may transmit the PDCCH scheduling the PDSCH thereof without theCIF. On the contrary, when the CIF is used through the upper-layersignaling, only one DL CC ‘A’ may transmit the PDCCH scheduling thePDSCH thereof or the PDSCH of another CC by using the CIF. In this case,DL CC ‘B’ and ‘C’ in which the PDCCH monitoring DL CC is not configureddoes not transmit the PDCCH.

General ACK/NACK Multiplexing Method

In a situation in which the terminal simultaneously needs to transmitmultiple ACKs/NACKs corresponding to multiple data units received froman eNB, an ACK/NACK mulplexign method based on PUCCH resource selectionmay be considered in order to maintain a single-frequency characteristicof the ACK/NACK signal and reduce ACK/NACK transmission power.

Together with ACK/NACK multiplexing, contents of ACK/NACK responses formultiple data units may be identified by combining a PUCCH resource anda resource of QPSK modulation symbols used for actual ACK/NACKtransmission.

For example, when one PUCCH resource may transmit 4 bits and four dataunits may be maximally transmitted, an ACK/NACK result may be identifiedin the eNB as shown in Table 3 given below.

TABLE 3 HARQ-ACK(0), HARQ-ACK(1), HARQ-ACK(2), n_(PUCCH) ⁽¹⁾ b(0),HARQ-ACK(3) b(1) ACK, ACK, ACK, ACK n_(PUCCH, 1) ⁽¹⁾ 1, 1 ACK, ACK, ACK,NACK/DTX n_(PUCCH, 1) ⁽¹⁾ 1, 0 NACK/DTX, NACK/DTX, NACK, DTXn_(PUCCH, 2) ⁽¹⁾ 1, 1 ACK, ACK, NACK/DTX, ACK n_(PUCCH, 1) ⁽¹⁾ 1, 0NACK, DTX, DTX, DTX n_(PUCCH, 0) ⁽¹⁾ 1, 0 ACK, ACK, NACK/DTX, NACK/DTXn_(PUCCH, 1) ⁽¹⁾ 1, 0 ACK, NACK/DTX, ACK, ACK n_(PUCCH, 3) ⁽¹⁾ 0, 1NACK/DTX, NACK/DTX, NACK/DTX, NACK n_(PUCCH, 3) ⁽¹⁾ 1, 1 ACK, NACK/DTX,ACK, NACK/DTX n_(PUCCH, 2) ⁽¹⁾ 0, 1 ACK, NACK/DTX, NACK/DTX, ACKn_(PUCCH, 0) ⁽¹⁾ 0, 1 ACK, NACK/DTX, NACK/DTX, NACK/DTX n_(PUCCH, 0) ⁽¹⁾1, 1 NACK/DTX, ACK, ACK, ACK n_(PUCCH, 3) ⁽¹⁾ 0, 1 NACK/DTX, NACK, DTX,DTX n_(PUCCH, 1) ⁽¹⁾ 0, 0 NACK/DTX, ACK, ACK, NACK/DTX n_(PUCCH, 2) ⁽¹⁾1, 0 NACK/DTX, ACK, NACK/DTX, ACK n_(PUCCH, 3) ⁽¹⁾ 1, 0 NACK/DTX, ACK,NACK/DTX, NACK/DTX n_(PUCCH, 1) ⁽¹⁾ 0, 1 NACK/DTX, NACK/DTX, ACK, ACKn_(PUCCH, 3) ⁽¹⁾ 0, 1 NACK/DTX, NACK/DTX, ACK, NACK/DTX n_(PUCCH, 2) ⁽¹⁾0, 0 NACK/DTX, NACK/DTX, NACK/DTX, ACK n_(PUCCH, 3) ⁽¹⁾ 0, 0 DTX, DTX,DTX, DTX N/A N/A

In Table 3 given above, HARQ-ACK(i) represents an ACK/NACK result for ani-th data unit. In Table 3 given above, discontinuous transmission (DTX)means that there is no data unit to be transmitted for the correspondingHARQ-ACK(i) or that the terminal may not detect the data unitcorresponding to the HARQ-ACK(i).

According to Table 3 given above, a maximum of four PUCCH resources(n_(PUCCH,0) ⁽¹⁾, n_(PUCCH,1) ⁽¹⁾, n_(PUCCH,2) ⁽¹⁾, and n_(PUCCH,3) ⁽¹⁾)are provided and b(0) and b(1) are two bits transmitted by using aselected PUCCH.

For example, when the terminal successfully receives all of four dataunits, the terminal transmits 2 bits (1,1) by using n_(PUCCH,1) ⁽¹⁾.

When the terminal fails to decoding in first and third data units andsucceeds in decoding in second and fourth data units, the terminaltransmits bits (1,0) by using n_(PUCCH,3) ⁽¹⁾.

In ACK/NACK channel selection, when there is at least one ACK, the NACKand the DTX are coupled with each other. The reason is that acombination of the PUCCH resource and the QPSK symbol may not allACK/NACK states. However, when there is no ACK, the DTX is decoupledfrom the NACK.

In this case, the PUCCH resource linked to the data unit correspondingto one definite NACK may also be reserved to transmit signals ofmultiple ACKs/NACKs.

Validation of PDCCH for Semi-Persistent Scheduling

Semi-persistent scheduling (SPS) is a scheduling scheme that allocatesthe resource to the terminal to be persistently maintained during aspecific time interval.

When a predetermined amount of data is transmitted for a specific timelike a voice over Internet protocol (VoIP), since the controlinformation need not be transmitted every data transmission interval forthe resource allocation, the waste of the control information may bereduced by using the SPS scheme. In a so-called semi-persistentscheduling (SPS) method, a time resource domain in which the resourcemay be allocated to the terminal is preferentially allocated.

In this case, in a semi-persistent allocation method, a time resourcedomain allocated to a specific terminal may be configured to haveperiodicity. Then, a frequency resource domain is allocated as necessaryto complete allocation of the time-frequency resource. Allocating thefrequency resource domain may be designated as so-called activation.When the semi-persistent allocation method is used, since the resourceallocation is maintained during a predetermined period by one-timesignaling, the resource need not be repeatedly allocated, and as aresult, signaling overhead may be reduced.

Thereafter, since the resource allocation to the terminal is notrequired, signaling for releasing the frequency resource allocation maybe transmitted from the base station to the terminal. Releasing theallocation of the frequency resource domain may be designated asdeactivation.

In current LTE, in which subframes the SPS is first transmitted/receivedthrough radio resource control (RRC) signaling for the SPS for theuplink and/or downlink is announced to the terminal. That is, the timeresource is preferentially designated among the time and frequencyresources allocated for the SPS through the RRC signaling. In order toannounce a usable subframe, for example, a period and an offset of thesubframe may be announced. However, since the terminal is allocated withonly the time resource domain through the RRC signaling, even though theterminal receives the RRC signaling, the terminal does not immediatelyperform transmission and reception by the SPS and the terminal allocatesthe frequency resource domain as necessary to complete the allocation ofthe time-frequency resource. Allocating the frequency resource domainmay be designated as deactivation and releasing the allocation of thefrequency resource domain may be designated as deactivation.

Therefore, the terminal receives the PDCCH indicating the activation andthereafter, allocate the frequency resource according to RB allocationinformation included in the received PDCCH and applies modulation andcode rate depending on modulation and coding scheme (MCS) information tostart transmission and reception according to the period and the offsetof the subframe allocated through the RRC signaling.

Next, when the terminal receives the PDCCH announcing the deactivationfrom the base station, the terminal stops transmission and reception.When the terminal receives the PDCCH indicating the activation orreactivation after stopping the transmission and reception, the terminalresumes the transmission and reception again with the period and theoffset of the subframe allocated through the RRC signaling by using theRC allocation, the MCS, and the like designated by the PDCCH. That is,the time resource is performed through the RRC signaling, but the signalmay be actually transmitted and received after receiving the PDCCHindicating the activation and reactivation of the SPS and the signaltransmission and reception stop after receiving the PDCCH indicating thedeactivation of the SPS.

When all conditions described below are satisfied, the terminal mayvalidate a PDCCH including an SPS indication. First, a CRC parity bitadded for a PDCCH payload needs to be scrambled with an SPS C-RNTI andsecond, a new data indicator (NDI) field needs to be set to 0. Herein,in the case of DCI formats 2, 2A, 2B, and 2C, the new data indicatorfield indicates one activated transmission block.

In addition, when each field used in the DCI format is set according toTables 4 and 5 given below, the validation is completed. When thevalidation is completed, the terminal recognizes that received DCIinformation is valid SPS activation or deactivation (alternatively,release). On the contrary, when the validation is not completed, theterminal recognizes that a non-matching CRC is included in the receivedDCI format.

Table 4 shows a field for validating the PDCCH indicating the SPSactivation.

TABLE 4 DCI format 0 DCI format 1/1A DCI format 2/2A/2B TPC command forset to ‘00’ N/A N/A scheduled PUSCH Cyclic shift DM RS set to ‘000’ N/AN/A Modulation and MSB is set to ‘0’ N/A N/A coding scheme andredundancy version HARQ process number N/A FDD: set to ‘000’ FDD: set to‘000’ TDD: set to ‘0000’ TDD: set to ‘0000’ Modulation and N/A MSB isset to ‘0’ For the enabled coding scheme transport block: MSB is set to‘0’ Redundancy N/A set to ‘00’ For the enabled version transport block:set to ‘00’

Table 5 shows a field for validating the PDCCH indicating the SPSdeactivation (alternatively, release).

TABLE 5 DCI format 0 DCI format 1A TPC command for scheduled set to ‘00’N/A PUSCH Cyclic shift DM RS set to ‘000’ N/A Modulation and coding setto ‘11111’ N/A scheme and redundancy version Resource block assignmentSet to all ‘1’s N/A and hopping resource allocation HARQ process numberN/A FDD: set to ‘000’ TDD: set to ‘0000’ Modulation and coding N/A setto ‘11111’ scheme Redundancy version N/A set to ‘00’ Resource blockassignment N/A Set to all ‘1’s

When the DCI format indicates SPS downlink scheduling activation, a TPCcommand value for the PUCCH field may be used as indexes indicating fourPUCCH resource values set by the upper layer.

PUCCH Piggybacking in Rel-8 LTE

FIG. 11 illustrates one example of transport channel processing of aUL-SCH in the wireless communication system to which the presentinvention can be applied.

In a 3GPP LTE system (=E-UTRA, Rel. 8), in the case of the UL, singlecarrier transmission having an excellent peak-to-average power ratio(PAPR) or cubic metric (CM) characteristic which influences theperformance of a power amplifier is maintained for efficient utilizationof the power amplifier of the terminal. That is, in the case oftransmitting the PUSCH of the existing LTE system, data to betransmitted may maintain the single carrier characteristic throughDFT-precoding and in the case of transmitting the PUCCH, information istransmitted while being loaded on a sequence having the single carriercharacteristic to maintain the single carrier characteristic. However,when the data to be DFT-precoded is non-contiguously allocated to afrequency axis or the PUSCH and the PUCCH are simultaneouslytransmitted, the single carrier characteristic deteriorates. Therefore,when the PUSCH is transmitted in the same subframe as the transmissionof the PUCCH as illustrated in FIG. 11, uplink control information (UCI)to be transmitted to the PUCCH is transmitted (piggyback) together withdata through the PUSCH.

Since the PUCCH and the PUSCH may not be simultaneously transmitted asdescribed above, the existing LTE terminal uses a method thatmultiplexes uplink control information (UCI) (CQI/PMI, HARQ-ACK, RI, andthe like) to the PUSCH region in a subframe in which the PUSCH istransmitted.

As one example, when the channel quality indicator (CQI) and/orprecoding matrix indicator (PMI) needs to be transmitted in a subframeallocated to transmit the PUSCH, UL-SCH data and the CQI/PMI aremultiplexed after DFT-spreading to transmit both control information anddata. In this case, the UL-SCH data is rate-matched by considering aCQI/PMI resource. Further, a scheme is used, in which the controlinformation such as the HARQ ACK, the RI, and the like punctures theUL-SCH data to be multiplexed to the PUSCH region.

FIG. 12 illustrates one example of a signal processing process of anuplink share channel of a transport channel in the wirelesscommunication system to which the present invention can be applied.

Herein, the signal processing process of the uplink share channel(hereinafter, referred to as “UL-SCH”) may be applied to one or moretransport channels or control information types.

Referring to FIG. 12, the UL-SCH transfers data to a coding unit in theform of a transport block (TB) once every a transmission time interval(TTI).

A CRC parity bit p₀, p₁, p₂, p₃, . . . p_(L−1) is attached to a bit ofthe transport block received from the upper layer (S120). In this case,A represents the size of the transport block and L represents the numberof parity bits. Input bits to which the CRC is attached are shown in b₀,b₁, b₂, b₃, . . . , b_(B−1). In this case, B represents the number ofbits of the transport block including the CRC.

b₀, b₁, b₂, b₃, . . . , b_(B−1) is segmented into multiple code blocks(CBs) according to the size of the TB and the CRC is attached tomultiple segmented CBs (S121). Bits after the code block segmentationand the CRC attachment are shown in c_(r0), c_(r1), c_(r2), c_(r3), . .. , c_(r(K) _(r) ⁻¹⁾. Herein, r represents No. (r=0, . . . , C−1) of thecode block and Kr represents the bit number depending on the code blockr. Further, C represents the total number of code blocks.

Subsequently, channel coding is performed (S122). Output bits after thechannel coding are shown in d_(r0) ^((i)), d_(r1) ^((i)), d_(r2) ^((i)),d_(r3) ^((i)), . . . , d_(r(D) _(r) ⁻¹⁾ ^((i)). In this case, irepresents an encoded stream index and may have a value of 0, 1, or 2.Dr represents the number of bits of the i-th encoded stream for the codeblock r. r represents the code block number (r=0, . . . , C−1) and Crepresents the total number of code blocks. Each code block may beencoded by turbo coding.

Subsequently, rate matching is performed (S123). Bits after the ratematching are shown in e_(r0), e_(r1), e_(r2), e_(r3), . . . , e_(r(E)_(r) ⁻¹⁾. In this case, r represents the code block number (r=0, . . . ,C−1) and C represents the total number of code blocks. Er represents thenumber of rate-matched bits of the r-th code block.

Subsequently, concatenation among the code blocks is performed again(S124). Bits after the concatenation of the code blocks is performed areshown in f₀, f₁, f₂, f₃, . . . , f_(G−1). In this case, G represents thetotal number of bits encoded for transmission and when the controlinformation is multiplexed with the UL-SCH, the number of bits used fortransmitting the control information is not included.

Meanwhile, when the control information is transmitted in the PUSCH,channel coding of the CQI/PMI, the RI, and the ACK/NACK which are thecontrol information is independently performed (S126, S127, and S128).Since different encoded symbols are allocated for transmitting eachcontrol information, the respective control information has differentcoding rates.

In time division duplex (TDD), as an ACK/NACK feedback mode, two modesof ACK/NACK bundling and ACK/NACK multiplexing are supported by anupper-layer configuration. ACK/NACK information bits for the ACK/NACKbundling are constituted by 1 bit or 2 bits and ACK/NACK informationbits for the ACK/NACK multiplexing are constituted by 1 to 4 bits.

After the concatenation among the code blocks in step S134, encoded bitsf₀, f₁, f₂, f₃, . . . , f_(G−1) of the UL-SCH data and encoded bits q₀,q₁, q₂, q₃, . . . , q_(N) _(L) _(·Q) _(CQI) ⁻¹ of the CQI/PMI aremultiplexed (S125). A multiplexed result of the data and the CQI/PMI isshown in g ₀, g ₁, g ₂, g ₃, . . . , g _(H′−1). In this case, g _(i)(i=0, . . . , H′−1) represents a column vector having a length of(Q_(m)·N_(L)). H=(G+N_(L)·Q_(CQI)) and H′=H/(H_(L)·Q_(m)). N_(L)represents the number of layers mapped to a UL-SCH transport block and Hrepresents the total number of encoded bits allocated to N_(L) transportlayers mapped with the transport block for the UL-SCH data and theCQI/PMI information.

Subsequently, the multiplexed data and CQI/PMI, a channel encoded RI,and the ACK/NACK are channel-interleaved to generate an output signal(S129).

Reference Signal (RS)

In the wireless communication system, since the data is transmittedthrough the radio channel, the signal may be distorted duringtransmission. In order for the receiver side to accurately receive thedistorted signal, the distortion of the received signal needs to becorrected by using channel information. In order to detect the channelinformation, a signal transmitting method know by both the transmitterside and the receiver side and a method for detecting the channelinformation by using an distortion degree when the signal is transmittedthrough the channel are primarily used. The aforementioned signal isreferred to as a pilot signal or a reference signal (RS).

When the data is transmitted and received by using the MIMO antenna, achannel state between the transmitting antenna and the receiving antennaneed to be detected in order to accurately receive the signal.Therefore, the respective transmitting antennas need to have individualreference signals.

The downlink reference signal includes a common RS (CRS) shared by allterminals in one cell and a dedicated RS (DRS) for a specific terminal.Information for demodulation and channel measurement may be provided byusing the reference signals.

The receiver side (that is, terminal) measures the channel state fromthe CRS and feeds back the indicators associated with the channelquality, such as the channel quality indicator (CQI), the precodingmatrix index (PMI), and/or the rank indicator (RI) to the transmittingside (that is, base station). The CRS is also referred to as acell-specific RS. On the contrary, a reference signal associated with afeed-back of channel state information (CSI) may be defined as CSI-RS.

The DRS may be transmitted through resource elements when datademodulation on the PDSCH is required. The terminal may receive whetherthe DRS is present through the upper layer and is valid only when thecorresponding PDSCH is mapped. The DRS may be referred to as theUE-specific RS or the demodulation RS (DMRS).

FIG. 13 illustrates a reference signal pattern mapped to a downlinkresource block pair in the wireless communication system to which thepresent invention can be applied.

Referring to FIG. 13, as a wise in which the reference signal is mapped,the downlink resource block pair may be expressed by one subframe in thetimedomain×12 subcarriers in the frequency domain. That is, one resourceblock pair has a length of 14 OFDM symbols in the case of a normalcyclic prefix (CP) (FIG. 13a ) and a length of 12 OFDM symbols in thecase of an extended cyclic prefix (CP) (FIG. 13b ). Resource elements(REs) represented as ‘0’, ‘1’, ‘2’, and ‘3’ in a resource block latticemean the positions of the CRSs of antenna port indexes ‘0’, ‘1’, ‘2’,and ‘3’, respectively and resource elements represented as ‘D’ means thepositon of the DRS.

Hereinafter, when the CRS is described in more detail, the CRS is usedto estimate a channel of a physical antenna and distributed in a wholefrequency band as the reference signal which may be commonly received byall terminals positioned in the cell. Further, the CRS may be used todemodulate the channel quality information (CSI) and data.

The CRS is defined as various formats according to an antenna array atthe transmitter side (base station). The 3GPP LTE system (for example,release-8) supports various antenna arrays and a downlink signaltransmitting side has three types of antenna arrays of three singletransmitting antennas, two transmitting antennas, and four transmittingantennas. When the base station uses the single transmitting antenna, areference signal for a single antenna port is arrayed. When the basestation uses two transmitting antennas, reference signals for twotransmitting antenna ports are arrayed by using a time divisionmultiplexing (TDM) scheme and/or a frequency division multiplexing (FDM)scheme. That is, different time resources and/or different frequencyresources are allocated to the reference signals for two antenna portswhich are distinguished from each other.

Moreover, when the base station uses four transmitting antennas,reference signals for four transmitting antenna ports are arrayed byusing the TDM and/or FDM scheme. Channel information measured by adownlink signal receiving side (terminal) may be used to demodulate datatransmitted by using a transmission scheme such as single transmittingantenna transmission, transmission diversity, closed-loop spatialmultiplexing, open-loop spatial multiplexing, or multi-user MIMO.

In the case where the MIMO antenna is supported, when the referencesignal is transmitted from a specific antenna port, the reference signalis transmitted to the positions of specific resource elements accordingto a pattern of the reference signal and not transmitted to thepositions of the specific resource elements for another antenna port.That is, reference signals among different antennas are not duplicatedwith each other.

A rule of mapping the CRS to the resource block is defined as below.

$\begin{matrix}{{k = {{6m} + {\left( {v + v_{shift}} \right){mod}\; 6}}}{l = \left\{ {{{\begin{matrix}{0,{N_{symb}^{DL} - 3}} & {{{if}\mspace{14mu} p}\; \in \left\{ {0,1} \right\}} \\1 & {{{if}\mspace{14mu} p}\; \in \left\{ {2,3} \right\}}\end{matrix}m} = 0},1,\ldots\mspace{14mu},{{{2 \cdot N_{RB}^{DL}} - {1m^{\prime}}} = {{m + N_{RB}^{\max,{DL}} - {N_{RB}^{DL}v}} = \left\{ {{\begin{matrix}0 & {{{if}\mspace{14mu} p} = {{0\mspace{14mu}{and}\mspace{14mu} l} = 0}} \\3 & {{{if}\mspace{14mu} p} = {{0\mspace{14mu}{and}\mspace{14mu} l} \neq 0}} \\3 & {{{if}\mspace{14mu} p} = {{1\mspace{14mu}{and}\mspace{14mu} l} = 0}} \\0 & {{{if}\mspace{14mu} p} = {{1\mspace{14mu}{and}\mspace{14mu} l} \neq 0}} \\{3\left( {n_{s}{mod}\; 2} \right)} & {{{if}\mspace{14mu} p} = 2} \\{3 + {3\left( {n_{s}{mod}\; 2} \right)}} & {{{if}\mspace{14mu} p} = 3}\end{matrix}v_{shift}} = {N_{ID}^{cell}{mod}\; 6}} \right.}}} \right.}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In Equation 1, k and l represent the subcarrier index and the symbolindex, respectively and p represents the antenna port. N_(symb) ^(DL)represents the number of OFDM symbols in one downlink slot and N_(RB)^(DL) represents the number of radio resources allocated to thedownlink. ns represents a slot index and, N_(ID) ^(cell) represents acell ID. mod represents an modulo operation. The position of thereference signal varies depending on the v_(shift) value in thefrequency domain. Since v_(shift) is subordinated to the cell ID, theposition of the reference signal has various frequency shift valuesaccording to the cell.

In more detail, the position of the CRS may be shifted in the frequencydomain according to the cell in order to improve channel estimationperformance through the CRS. For example, when the reference signal ispositioned at an interval of three subcarriers, reference signals in onecell are allocated to a 3k-th subcarrier and a reference signal inanother cell is allocated to a 3k+1-th subcarrier. In terms of oneantenna port, the reference signals are arrayed at an interval of sixresource elements in the frequency domain and separated from a referencesignal allocated to another antenna port at an interval of threeresource elements.

In the time domain, the reference signals are arrayed at a constantinterval from symbol index 0 of each slot. The time interval is defineddifferently according to a cyclic shift length. In the case of thenormal cyclic shift, the reference signal is positioned at symbolindexes 0 and 4 of the slot and in the case of the extended CP, thereference signal is positioned at symbol indexes 0 and 3 of the slot. Areference signal for an antenna port having a maximum value between twoantenna ports is defined in one OFDM symbol. Therefore, in the case oftransmission of four transmitting antennas, reference signals forreference signal antenna ports 0 and 1 are positioned at symbol indexes0 and 4 (symbol indexes 0 and 3 in the case of the extended CP) andreference signals for antenna ports 2 and 3 are positioned at symbolindex 1 of the slot. The positions of the reference signals for antennaports 2 and 3 in the frequency domain are exchanged with each other in asecond slot.

Hereinafter, when the DRS is described in more detail, the DRS is usedfor demodulating data. A precoding weight used for a specific terminalin the MIMO antenna transmission is used without a change in order toestimate a channel associated with and corresponding to a transmissionchannel transmitted in each transmitting antenna when the terminalreceives the reference signal.

The 3GPP LTE system (for example, release-8) supports a maximum of fourtransmitting antennas and a DRS for rank 1 beamforming is defined. TheDRS for the rank 1 beamforming also means a reference signal for antennaport index 5.

A rule of mapping the DRS to the resource block is defined as below.Equation 2 shows the case of the normal CP and Equation 3 shows the caseof the extended CP.

$\begin{matrix}{{k = {{\left( k^{\prime} \right){mod}\; N_{sc}^{RB}} + {N_{sc}^{RB} \cdot n_{PRB}}}}{k^{\prime} = \left\{ {{\begin{matrix}{{4m^{\prime}} + v_{shift}} & {{{if}\mspace{14mu} l} \in \left\{ {2,3} \right\}} \\{{4m^{\prime}} + {\left( {2 + v_{shift}} \right){mod}\; 4}} & {{{if}\mspace{14mu} l} \in \left\{ {5,6} \right\}}\end{matrix}l} = \left\{ {{\begin{matrix}3 & {l^{\prime} = 0} \\6 & {l^{\prime} = 1} \\2 & {l^{\prime} = 2} \\5 & {l^{\prime} = 3}\end{matrix}l^{\prime}} = \left\{ {{{\begin{matrix}{0,1} & {{{if}\mspace{14mu} n_{s}{mod}\; 2} = 0} \\{2,3} & {{{if}\mspace{14mu} n_{s}{mod}\; 2} = 1}\end{matrix}m^{\prime}} = 0},1,\ldots\mspace{14mu},{{{3N_{RB}^{PDSCH}} - {1v_{shift}}} = {N_{ID}^{cell}{mod}\; 3}}} \right.} \right.} \right.}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack \\{{k = {{\left( k^{\prime} \right){mod}\; N_{sc}^{RB}} + {N_{sc}^{RB} \cdot n_{PRB}}}}{k^{\prime} = \left\{ {{\begin{matrix}{{3m^{\prime}} + v_{sluft}} & {{{if}\mspace{14mu} l} = 4} \\{{3m^{\prime}} + {\left( {2 + v_{shift}} \right){mod}\; 3}} & {{{if}\mspace{14mu} l} = 1}\end{matrix}l} = \left\{ {{\begin{matrix}4 & {l^{\prime} \in \left\{ {0,2} \right\}} \\1 & {l^{\prime} = 1}\end{matrix}l^{\prime}} = \left\{ {{{\begin{matrix}0 & {{{if}\mspace{14mu} n_{s}{mod}\; 2} = 0} \\{1,2} & {{{if}\mspace{14mu} n_{s}{mod}\; 2} = 1}\end{matrix}m^{\prime}} = 0},1,\ldots\mspace{14mu},{{{4N_{RB}^{PDSCH}} - {1v_{shift}}} = {N_{ID}^{cell}{mod}\; 3}}} \right.} \right.} \right.}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$

In Equations 2 and 3, k and l represent the subcarrier index and thesymbol index, respectively and p represents the antenna port. N_(sc)^(RB) represents the size of the resource block in the frequency domainand is expressed as the number of subcarriers. n_(PRB) represents thenumber of physical resource blocks. N_(RB) ^(PDSCH) represents afrequency band of the resource block for the PDSCH transmission. nsrepresents the slot index and N_(ID) ^(cell) represents the cell ID. modrepresents the modulo operation. The position of the reference signalvaries depending on the v_(shift) value in the frequency domain. Sincev_(shift) is subordinated to the cell ID, the position of the referencesignal has various frequency shift values according to the cell.

Sounding Reference Signal (SRS)

The SRS is primarily used for the channel quality measurement in orderto perform frequency-selective scheduling and is not associated withtransmission of the uplink data and/or control information. However, theSRS is not limited thereto and the SRS may be used for various otherpurposes for supporting improvement of power control and variousstart-up functions of terminals which have not been scheduled. Oneexample of the start-up function may include an initial modulation andcoding scheme (MCS), initial power control for data transmission, timingadvance, and frequency semi-selective scheduling. In this case, thefrequency semi-selective scheduling means scheduling that selectivelyallocates the frequency resource to the first slot of the subframe andallocates the frequency resource by pseudo-randomly hopping to anotherfrequency in the second slot.

Further, the SRS may be used for measuring the downlink channel qualityon the assumption that the radio channels between the uplink and thedownlink are reciprocal. The assumption is valid particularly in thetime division duplex in which the uplink and the downlink share the samefrequency spectrum and are divided in the time domain.

Subframes of the SRS transmitted by any terminal in the cell may beexpressed by a cell-specific broadcasting signal. A 4-bit cell-specific‘srsSubframeConfiguration’ parameter represents 15 available subframearrays in which the SRS may be transmitted through each radio frame. Bythe arrays, flexibility for adjustment of the SRS overhead is providedaccording to a deployment scenario.

A 16-th array among them completely turns off a switch of the SRS in thecell and is suitable primarily for a serving cell that serves high-speedterminals.

FIG. 14 illustrates an uplink subframe including a sounding referencesignal symbol in the wireless communication system to which the presentinvention can be applied.

Referring to FIG. 14, the SRS is continuously transmitted through a lastSC FDMA symbol on the arrayed subframes. Therefore, the SRS and the DMRSare positioned at different SC-FDMA symbols.

The PUSCH data transmission is not permitted in a specific SC-FDMAsymbol for the SRS transmission and consequently, when sounding overheadis highest, that is, even when the SRS symbol is included in allsubframes, the sounding overhead does not exceed approximately 7%.

Each SRS symbol is generated by a base sequence (random sequence or asequence set based on Zadoff-Ch (ZC)) associated with a given time wiseand a given frequency band and all terminals in the same cell use thesame base sequence. In this case, SRS transmissions from a plurality ofterminals in the same cell in the same frequency band and at the sametime are orthogonal to each other by different cyclic shifts of the basesequence to be distinguished from each other.

SRS sequences from different cells may be distinguished for each otherby allocating different base sequences to respective cells, butorthogonality among different base sequences is not assured.

Coordinated Multi-Point Transmission and Reception (COMP)

According to a demand of LTE-advanced, CoMP transmission is proposed inorder to improve the performance of the system. The CoMP is also calledco-MIMO, collaborative MIMO, network MIMO, and the like. It isanticipated that the CoMP will improves the performance of the terminalpositioned at a cell edge and improve an average throughput of the cell(sector).

In general, inter-cell interference decreases the performance and theaverage cell (sector) efficiency of the terminal positioned at the celledge in a multi-cell environment in which a frequency reuse index is 1.In order to alleviate the inter-cell interference, the LTE system adoptsa simple passive method such as fractional frequency reuse (FFR) in theLTE system so that the terminal positioned at the cell edge hasappropriate performance efficiency in an interference-limitedenvironment. However, a method that reuses the inter-cell interferenceor alleviates the inter-cell interference as a signal (desired signal)which the terminal needs to receive is more preferable instead ofreduction of the use of the frequency resource for each cell. The CoMPtransmission scheme may be adopted in order to achieve theaforementioned object.

The CoMP scheme which may be applied to the downlink may be classifiedinto a joint processing (JP) scheme and a coordinatedscheduling/beamforming (CS/CB) scheme.

In the JP scheme, the data may be used at each point (base station) in aCoMP wise. The CoMP wise means a set of base stations used in the CoMPscheme. The JP scheme may be again classified into a joint transmissionscheme and a dynamic cell selection scheme.

The joint transmission scheme means a scheme in which the signal issimultaneously transmitted through a plurality of points which are allor fractional points in the CoMP wise. That is, data transmitted to asingle terminal may be simultaneously transmitted from a plurality oftransmission points. Through the joint transmission scheme, the qualityof the signal transmitted to the terminal may be improved regardless ofcoherently or non-coherently and interference with another terminal maybe actively removed.

The dynamic cell selection scheme means a scheme in which the signal istransmitted from the single point through the PDSCH in the CoMP wise.That is, data transmitted to the single terminal at a specific time istransmitted from the single point and data is not transmitted to theterminal at another point in the CoMP wise. The point that transmits thedata to the terminal may be dynamically selected.

According to the CS/CB scheme, the CoMP wise performs beamformingthrough coordination for transmitting the data to the single terminal.That is, the data is transmitted to the terminal only in the servingcell, but user scheduling/beamforming may be determined throughcoordination of a plurality of cells in the CoMP wise.

In the case of the uplink, CoMP reception means receiving the signaltransmitted by the coordination among a plurality of points which aregeographically separated. The CoMP scheme which may be applied to theuplink may be classified into a joint reception (JR) scheme and thecoordinated scheduling/beamforming (CS/CB) scheme.

The JR scheme means a scheme in which the plurality of points which areall or fractional points receives the signal transmitted through thePDSCH in the CoMP wise. In the CS/CB scheme, only the single pointreceives the signal transmitted through the PDSCH, but the userscheduling/beamforming may be determined through the coordination of theplurality of cells in the CoMP wise.

Cross-CC Scheduling and E-PDCCH Scheduling

In the existing 3GPP LTE Rel-10 system, if a cross-CC schedulingoperation is defined in an aggregation situation for a plurality of CCs(component carrier=(serving) cell), one CC may be preset to be able toreceive DL/UL scheduling from only one specific CC (i.e., scheduling CC)(namely, to be able to receive DL/UL grant PDCCH for the correspondingscheduled CC).

The corresponding scheduling CC may basically perform a DL/UL schedulingfor the scheduling CC itself.

In other words, the SS for the PDCCH scheduling the scheduling/scheduledCC in the cross-CC scheduling relation may come to exist in the controlchannel area of the scheduling CC.

Meanwhile, in the LTE system, CFDD DL carrier or TDD DL subframes usefirst n OFDM symbols of the subframe for PDCCH, PHICH, PCFICH and thelike which are physical channels for transmission of various controlinformations and use the rest of the OFDM symbols for PDSCHtransmission.

At this time, the number of symbols used for control channeltransmission in each subframe is dynamically transmitted to the UEthrough the physical channel such as PCFICH or is semi-staticallytransmitted to the UE through RRC signaling.

At this time, particularly, value n may be set by 1 to 4 symbolsdepending on the subframe characteristic and system characteristic(FDD/TDD, system bandwidth, etc.).

Meanwhile, in the existing LTE system, PDCCH, which is the physicalchannel for transmitting DL/UL scheduling and various controlinformation, may be transmitted through limited OFDM symbols.

Hence, the enhanced PDCCH (i.e., E-PDCCH), which is more freelymultiplexed in PDSCH and FDM/TDM scheme, may be introduced instead ofthe control channel which is transmitted through the OFDM which isseparated from the PDSCH like PDCCH.

FIG. 15 illustrates an example of multiplexing legacy PDCCH, PDSCH andE-PDCCH.

Here, the legacy PDCCH may be expressed as L-PDCCH.

FIG. 16 is a diagram illustrating a cell classification in a system thatsupports the carrier aggregation.

Referring to FIG. 16, a configured cell is a cell that should becarrier-merged based on a measurement report among the cells of a BS maybe configured for each terminal. The configured cell may reserve aresource for an ACK/NACK transmission for a PDSCH transmissionbeforehand. An activated cell is a cell that is configured to transmitPDSCH/PUSCH actually among the configured cells, and performs a ChannelState Information (CSI) report for the PDSCH/PUSCH transmission and aSounding Reference Signal (SRS) transmission. A de-activated cell is acell that does not transmit the PDSCH/PUSCH transmission by a command ofBS or a timer operation, may also stop the CSI report and the SRStransmission.

Synchronization Signal/Sequence (SS)

An SS includes a primary (P)-SS and a secondary (S)-SS, and correspondsto a signal used when a cell search is performed.

FIG. 17 is a diagram illustrating a frame structure used for an SStransmission in a system that uses a normal cyclic prefix (CP). FIG. 10is a diagram illustrating a frame structure used for an SS transmissionin a system that uses an extended CP.

The SS is transmitted in 0th subframe and second slot of the fifthsubframe, respectively, considering 4.6 ms which is a Global System forMobile communications (GSM) frame length for the easiness of aninter-Radio Access Technology (RAT) measurement, and a boundary for thecorresponding radio frame may be detected through the S-SS. The P-SS istransmitted in the last OFDM symbol of the corresponding slot and theS-SS is transmitted in the previous OFDM symbol of the P-SS.

The SS may transmit total 504 physical cell IDs through the combinationof 3 P-SSs and 168 S-SSs. In addition, the SS and the PBCH aretransmitted within 6 RBs at the center of a system bandwidth such that aterminal may detect or decode them regardless of the transmissionbandwidth.

A transmission diversity scheme of the SS is to use a single antennaport only and not separately used in a standard. That is, thetransmission diversity scheme of the SS uses a single antennatransmission or a transmission technique transparent to a terminal(e.g., Precoder Vector Switching (PVS), Time-Switched Transmit Diversity(TSTD) and Cyclic-Delay Diversity (CDD)).

1. P-SS Sign

Zadoff-Chu (ZC) sequence of length 63 in frequency domain may be definedand used as a sequence of the P-SS. The ZC sequence is defined byEquation 4, a sequence element, n=31 that corresponds to a DC subcarrieris punctured. In Equation 4, N_zc=63.

$\begin{matrix}{{d_{u}(n)} = e^{{- j}\frac{\pi\;{{un}{({n + 1})}}}{N_{ZC}}}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack\end{matrix}$

Among 6 RBs (=7 subcarriers) positioned at the center of frequencydomain, the remaining 9 subcarriers are always transmitted in zerovalue, which makes it easy to design a filter for performingsynchronization. In order to define total three P-SSs, the value ofu=29, 29 and 34 may be used in Equation 4. In this case, since 29 and 34have the conjugate symmetry relation, two correlations may besimultaneously performed. Here, the conjugate symmetry means Equation 5.By using the characteristics, it is possible to implement one shotcorrelater for u=29 and 43, and accordingly, about 33.3% of total amountof calculation may be decreased.d _(n)(n)=(−1)^(n)(d _(N) _(ZC) _(−u)(n))*, when N _(ZC) is even number.d _(n)(n)=(d _(N) _(ZC) _(−u)(n))*, when N _(ZC) is oddnumber.  [Equation 5]

2. S-SS Sign

The sequence used for the S-SS is combined with two interleavedm-sequences of length 31, and 168 cell group IDs are transmitted bycombining two sequences. The m-sequence as the SSS sequence is robust inthe frequency selective environment, and may be transformed to thehigh-speed m-sequence using the Fast Hadamard Transform, thereby theamount of operations being decreased. In addition, the configuration ofSSS using two short codes is proposed to decrease the amount ofoperations of terminal.

FIG. 19 is a diagram illustrating two sequences in a logical regionbeing mapped to a physical region by being interleaved.

Referring to FIG. 19, when two m-sequences used for generating the S-SSsign are defined by S1 and S2, in the case that the S-SS (S1, S2) ofsubframe 0 transmits the cell group ID with the combination, the S-SS(S2, S1) of subframe 5 is transmitted with being swapped, therebydistinguishing the 10 ms frame boundary. In this case, the SSS sign usesthe generation polynomial x5+x2+1, and total 31 signs may be generatedthrough the circular shift.

In order to improve the reception performance, two different P-SS-basedsequences are defined and scrambled to the S-SS, and scrambled to S1 andS2 with different sequences. Later, by defining the S1-based scramblingsign, the scrambling is performed to S2. In this case, the sign of S-SSis exchanged in a unit of 5 ms, but the P-SS-based scrambling sign isnot exchanged. The P-SS-based scrambling sign is defined by six circularshift versions according to the P-SS index in the m-sequence generatedfrom the generation polynomial x5+x2+1, and the S1-based scrambling signis defined by eight circular shift versions according to the S1 index inthe m-sequence generated from the generation polynomial x5+x4+x2+x1+1.

The contents below exemplify an asynchronous standard of the LTE system.

-   -   A terminal may monitor a downlink link quality based on a        cell-specific reference signal in order to detect a downlink        radio link quality of PCell.    -   A terminal may estimate a downlink radio link quality for the        purpose of monitoring the downlink radio link quality of PCell,        and may compare it with Q_out and Q_in, which are thresholds.    -   The threshold value Q_out may be defined as a level in which a        downlink radio link is not certainly received, and may        correspond to a block error rate 10% of a hypothetical PDCCH        transmission considering a PCFICH together with transmission        parameters.    -   The threshold value Q_in may be defined as a downlink radio link        quality level, which may be great and more certainly received        than Q_out, and may correspond to a block error rate 2% of a        hypothetical PDCCH transmission considering a PCFICH together        with transmission parameters.

Narrow Band (NB) LTE Cell Search

In the NB-LTE, although a cell search may follow the same rule as theLTE, there may be an appropriate modification in the sequence design inorder to increase the cell search capability.

FIG. 20 is a diagram illustrating a frame structure to which M-PSS andM-SSS are mapped. In the present disclosure, an M-PSS designates theP-SS in the NB-LTE, and an M-SSS designates the S-SS in the NB-LTE. TheM-PSS may also be designated to ‘NB-PSS’ and the M-SSS may also bedesignated to ‘NB-SSS’.

Referring to FIG. 20, in the case of the M-PSS, a single primarysynchronization sequence/signal may be used. (M-)PSS may be spanned upto 9 OFDM symbol lengths, and used for determining subframe timing aswell as an accurate frequency offset.

This may be interpreted that a terminal may use the M-PSS for acquiringtime and frequency synchronization with a BS. In this case, (M-)PSS maybe consecutively located in time domain.

The M-SSS may be spanned up to 6 OFDM symbol lengths, and used fordetermining the timing of a cell identifier and an M-frame. This may beinterpreted that a terminal may use the M-SSS for detecting anidentifier of a BS. In order to support the same number as the number ofcell identifier groups of the LTE, 504 different (M-)SSS may bedesigned.

Referring to the design of FIG. 20, the M-PSS and the M-SSS are repeatedevery 20 ms average, and existed/generated four times in a block of 80ms. In the subframes that include synchronization sequences, the M-PSSoccupies the last 9 OFDM symbols. The M-SSS occupies 6th, 7th, 10th, 11th, 13th and 14th OFDM symbols in the case of normal CP, and occupies5th, 6th, 9th, 11th and 12th OFDM symbols in the case of extended CP.

The 9 OFDM symbols occupied by the M-PSS may be selected to support forthe in-band disposition between LTE carriers. This is because the firstthree OFDM symbols are used to carry a PDCCH in the hosting LTE systemand a subframe includes minimum twelve OFDM symbols (in the case ofextended CP).

In the hosting LTE system, a cell-specific reference signal (CRS) istransmitted, and the resource elements that correspond to the M-PSS maybe punctured in order to avoid a collision. In the NB-LTE, a specificposition of M-PSS/M-SSS may be determined to avoid a collision with manylegacy LTE signals such as the PDCCH, the PCFICH, the PHICH and/or theMBSFN.

In comparison with the LTE, the synchronization sequence design in theNB-LTE may be different.

This may be performed in order to attain a compromise between decreasedmemory consumption and faster synchronization in a terminal. Since theM-SSS is repeated four times in 80 ms duration, a slight designmodification for the M-SSS may be required in the 80 ms duration inorder to solve a timing uncertainty.

Structure of M-PSS and M-SSS

In the LTE, the PSS structure allows the low complexity design of timingand frequency offset measuring instrument, and the SSS is designed toacquire frame timing and to support unique 504 cell identifiers.

In the case of In-band and Guard-band of the LTE, the disposition of CPin the NB-LTE may be selected to match the CP in a hosting system. Inthe case of standalone, the extended CP may be used for matching atransmitter pulse shape for exerting the minimum damage to the hostingsystem (e.g., GSM).

A single M-PSS may be clearly stated in the N-LTE of the LTE. In theprocedure of PSS synchronization of the LTE, for each of PSSs, aspecific number of frequency speculations may be used for the coarseestimation of symbol timing and frequency offset.

Such an adaption of the procedure in the NB-LTE may increase the processcomplexity of a receiver according to the use of a plurality offrequency assumptions. In order to solve the problem, a sequenceresembling of the Zadoff-Chu sequence which is differentially decoded intime domain may be proposed for the M-PSS. Since the differentialdecoding is performed in a transmission process, the differentialdecoding may be performed during the processing time of a receiver.Consequently, a frequency offset may be transformed from the consecutiverotation for symbols to the fixed phase offset with respect to thecorresponding symbols.

FIG. 21 is a diagram illustrating a method for generating M-PSSaccording to an embodiment of the present invention.

Referring to FIG. 21, first, when starting with a basic sequence oflength 107 as a basis in order to generate an M-PSS, Equation 6 belowmay be obtained.

$\begin{matrix}{{{c(n)} = e^{- \frac{j\;\pi\;{{un}{({n + 1})}}}{N}}},{n = \left\{ {0,1,2,\ldots\mspace{11mu},106} \right\}}} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack\end{matrix}$

The basic sequence c(n) may be differentially decoded in order to obtaind(n) sequence as represented in Equation 7.d(n+1)=d(n)c(n),n={0,1,2, . . . ,106},d(0)=1,  [Equation 7]

The d(n) sequence is divided into 9 sub sequences, and each sub sequencehas a length 12 and a sampling rate of 130 kHz. The 120-point FFT isperformed for each of 9 sub sequences, and each sequence may beoversampled 128/12 times up to 1.92 MHz sampling rate using 128 IFFTzero padding. Consequently, each sub sequence may be mapped to 12subcarriers for 9 OFDM symbols, respectively.

Each of the sub sequences is mapped to a single OFDM symbol, and theM-PSS may occupy total 9 OFDM symbols since total 9 sub sequences areexisted. Total length of the M-PSS may be 1234(=(128+9)*9+1) when thenormal CP of 9 samples are used, and may be 1440 when the extended CP isused.

The M-PSS which is going to be actually used during the transmission isnot required to be generated every time using complex procedure in atransmitter/receiver in the same manner. The complexity coefficient(i.e., t_u(n)) that corresponds to the M-PSS may be generated inoffline, and directly stored in the transmitter/receiver. In addition,even in the case that the M-PSS is generated in 1.92 MHz, the occupationbandwidth may be 180 kHz.

Accordingly, in the case of performing the procedure related to time andfrequency offset measurements using the M-PSS in a receiver, thesampling rate of 192 kHz may be used for all cases. This maysignificantly decrease the complexity of receiver in the cell search.

In comparison with the LTE, the frequency in which the M-PSS isgenerated in the NB-LTE causes slightly greater overhead than the PSS inthe LTE. More particularly, the synchronization sequence used in the LTEoccupies 2.86% of the entire transmission resources, and thesynchronization sequence used in the NB-LTE occupies about 5.36% of theentire transmission resources. Such an additional overhead has an effectof decreasing memory consumption as well as the synchronization timethat leads to the improved battery life and the lower device price.

The M-SSS is designed in frequency domain and occupies 12 subcarriers ineach of 6 OFDM symbols. Accordingly, the number of resource elementsdedicated to the M-SSS may be 72. The M-SSS includes the ZC sequence ofa single length 61 which are padded by eleven ‘0’s on the startingpoint.

In the case of the extended CP, the first 12 symbols of the M-SSS may bediscarded, and the remaining symbols may be mapped to the valid OFDMsymbols, which cause to discard only a single symbol among the sequenceof length 61 since eleven ‘0’s are existed on the starting point. Thediscard of the symbol causes the slight degradation of the correlationproperty of other SSS.

The cyclic shift of a sequence and the sequence for different roots mayeasily provide specific cell identifiers up to 504. The reason why theZC sequence is used in the NB-LTE in comparison with the LTE is todecrease the error detection rate. Since a common sequence for twodifferent cell identifier groups is existed, an additional procedure isrequired in the LTE.

Since the M-PSS/M-SSS occur four times within the block of 80 ms, theLTE design of the SSS cannot be used for providing accurate timinginformation within the corresponding block. This is because the specialinterleaving structure that may determine only two positions.Accordingly, a scrambling sequence may be used in an upper part of theZC sequence in order to provide the information of frame timing. Fourscrambling sequences may be required to determine four positions withinthe block of 80 ms, which may influence on acquiring the accuratetiming.

FIG. 22 is a diagram illustrating a method for generating M-SSSaccording to an embodiment of the present invention.

Referring to FIG. 22, the M-SSS may be defined ass_p,q(n)=a_p(n)·b_q(n). Herein, p={0, 1, . . . , 503} represents cellidentifiers and q={0, 1, 2, 3} determines the position of the M-SSS(i.e., the number of M-SSS within the block of 80 ms which is generatedbefore the latest SSS). In addition, a_p(n) and b_q(n) may be determinedby Equations 8 and 9 below.

$\begin{matrix}\begin{matrix}{{{a_{p}(n)} = 0},} & {n = {\left\{ {{0 - 4},{66 - 71}} \right\} ↵}} \\{{= {a_{p}\left( {n - k_{p} - 5} \right)}},} & {n = {\left\{ {5,6,\ldots\mspace{14mu},65} \right\} ↵}} \\{{{a_{p}(n)} = e^{- \frac{j\;\pi\;{m{(p)}}{n{({n + 1})}}}{61}}},} & {n = {\left\{ {0,1,\ldots\mspace{14mu},61} \right\} ↵}}\end{matrix} & \left\lbrack {{Equation}\mspace{14mu} 8} \right\rbrack \\\frac{\begin{matrix}{{b_{q}(n)} = {b\left( {{mod}\left( {{n - l_{q}},63} \right)} \right)}} & {{n = \left\{ {0,1,\ldots\mspace{14mu},60} \right\}},} \\\; & {{q = \left\{ {0,1,2,3} \right\}},} \\\; & {{l_{0} = 0},{l_{1} = 3},{l_{2} = 7},{l_{3} = {11↵}}}\end{matrix}}{\begin{matrix}{{{b\left( {n + 6} \right)} = {{mod}\left( {{{b(n)} + {b\left( {n + 1} \right)}},2} \right)}},} & {{n = \left\{ {0,1,{\ldots\mspace{14mu} 55}} \right\}},↵} \\{{{b(0)} = 1},{{b(m)} = 0},} & {m = {\left\{ {1,2,3,4,5} \right\} ↵}}\end{matrix}} & \left\lbrack {{Equation}\mspace{14mu} 9} \right\rbrack\end{matrix}$

Referring to Equation 8, a_p(n) is the ZC sequence and determines a cellidentifier group. m(p) and cyclic shift k_p may be used for providing aspecific cell identifier. Referring to Equation 9, b_q(n) may be thescrambling sequence that includes a cyclic shift of the basic sequenceb_(n), and may be used for indicating the position of the M-SSS in theM-frame in order to acquire the frame timing. The cyclic shift l_q maybe determined according to the value q.

The value of m(p) with respect to the specific p may be determined suchas m(p)=1+mod(p, 61), the value of k_p may be determined such ask_p=7[p/61].

FIG. 23 illustrates an example of a method for implementing M-PSS towhich the method proposed in the present disclosure can be applied.

Particularly, FIG. 23 shows a method for generating an M-PSS using acomplementary Golay sequence.

As shown in FIG. 23, using a complementary Golay sequence pair, a CGSthat is going to be transmitted to each OFDM symbol is selected (i.e.,select a(n) or b(n)).

Next, in the case of using a cover code, c(1) to c(N) may be multipliedto each CGS, and in the case of not using the cover code, 1 may beinputted to all of c(n).

Subsequently, the DFT and the IFFT are performed for each symbol, andtransmitted to each OFDM symbol on time domain.

Additionally, the ZC sequence of length 12 may also generate a sequencethat is going to be transmitted to each OFDM symbol.

In this case, by using the same method applied in FIG. 23, the M-PSS maybe implemented.

NB (Narrow Band)-LTE System

Hereinafter, NB-LTE (or NB-IoT) system will be described.

The UL of NB-LTE is based on SC-FDMA, and this is a special case ofSC-FDMA and may flexibly allocate the bandwidth of the UE includingsingle tone transmission.

One important aspect for the UL SC-FDMA is to enable time of a multipleof co-scheduled UEs coincide with each other so that the arrival timedifference in the base station to be within the cyclic prefix (CP).

Ideally, the UL 15 kHz subcarrier spacing should be used in NB-LTE, butthe time-accuracy, which may be achieved when detecting PRACH from theUEs in a very poor coverage condition, should be considered.

Hence, CP duration needs to be increased.

One way to achieve the above purpose is to reduce the subcarrier spacingfor NB-LTE M-PUSCH to 2.5 kHz by dividing 15 kHz subcarrier spacing by6.

Another motive for reducing subcarrier spacing is to allow a usermultiplexing of a high level.

For example, one user is basically allocated to one subcarrier.

This is more effective for UEs in a condition that the coverage is verylimited like UEs having no benefit from allocation of a high bandwidthwhile the capacity increases due to the simultaneous use of the maximumTX power of a multiple of UEs.

SC-FDMA is used for transmission of a multiple of tones in order tosupport a higher data rate along with the additional PAPR reductiontechnology.

The UL NB-LTE includes 3 basic channels including M-PRACH, M-PUCCH andM-PUSCH.

The design of M-PUCCH discuses at least three alternative plans asfollows.

-   -   One tone in each edge of the system bandwidth    -   UL control information transmission on M-PRACH or M-PUSCH    -   Not having dedicated UL control channel

Time-Domain Frame and Structure

In the UL of NB-LTE having 2.5 kHz subcarrier spacing, the wirelessframe and the subframe are defined as 60 ms and 6 ms, respectively.

As in the DL of NB-LTE, M-frame and M-subframe are defined in the samemanner in the UL link of the NB-LTE.

FIG. 24 illustrates how the UL numerology is stretched in the timedomain.

The NB-LTE carrier includes 5 PRBs in the frequency domain. Each NB-LTEPRB includes 12 subcarriers.

The UL frame structure based on 2.5 kHz subcarrier spacing isillustrated in FIG. 17.

FIG. 24 illustrates an example of UL numerology which is stretched inthe time domain when the subcarrier spacing is reduced from 15 kHz to2.5 kHz.

FIG. 25 illustrates an example of time units for the UL of NB-LTE basedon the 2.5 kHz subcarrier spacing.

Operation System of NB-LTE System

FIG. 26 illustrates an example of an operation system of NB-LTE systemto which the method proposed in the present specification is applicable.

Specifically, FIG. 26(a) illustrates an in-band system, FIG. 26(b)illustrates a guard-band system, and FIG. 26(c) illustrates astand-alone system.

The in-band system may be expressed as an in-band mode, the guard-bandsystem may be expressed as a guard-band mode, and the stand-alone systemmay be expressed as a stand-alone mode.

The in-band system of FIG. 26(a) indicates a system or mode which uses aspecific 1 RB within the legacy LTE band for NB-LTE (or LTE-NB) and maybe operated by allocating some resource blocks of the LTE systemcarrier.

The guard-band system of FIG. 25(b) indicates a system or mode whichuses NB-LTE in the space which is reserved for the guard band of thelegacy LTE band and may be operated by allocating the guard-band of LTEcarrier which is not used as the resource block in the LTE system.

The legacy LTE band includes the minimum 100 kHz at the last of each LTEband.

In order to use 200 kHz, 2 non-continuous guardbands may be used.

The in-band system and the guard-band system indicate the structurewhere NB-LTE co-exists within the legacy LTE band.

In contrast, the standalone system of FIG. 26(c) indicates a system ormode which is independently configured from the legacy LTE band and maybe operated by separately allocating the frequency band (futurereallocated GSM carrier) which is used in the GERAN.

FIG. 27 illustrates an example of an NB-frame structure of 15 kHzsubcarrier spacing to which the method proposed in the presentspecification is applicable.

As illustrated in FIG. 27, it may be understood that the NB-framestructure for 15 kHz subcarrier spacing is the same as the framestructure of the legacy system (LTE system).

Namely, 10 ms NB-frame includes 10 1 ms NB-subframes, and 1 msNB-subframe includes 2 0.5 ms NB-slots.

Further, 0.5 ms NB-slot includes 7 OFDM symbols.

FIG. 28 illustrates an example of NB-frame structure for 3.75 kHzsubcarrier spacing to which the method proposed in the presentspecification is applicable.

Referring to FIG. 28, 10 ms NB-frame includes 5 2 ms NB-subframes, and 2ms NB-subframe includes 7 OFDM symbols one guard-period (GP).

The 2 ms NB-subframe may also be expressed as NB-slot or NB-RU (resourceunit), etc.

FIG. 29 illustrates an example of NB subframe structure in 3.75 kHzsubcarrier spacing to which the method proposed in the presentspecification is applicable.

FIG. 29 shows the correspondence between legacy LTE subframe structureand 3.75 subframe structure.

Referring to FIG. 29, subframe (2 ms) of 3.75 kHz corresponds to 2 1 mssubframes (or 1 ms TTIs) of the legacy LTE.

Hereinafter, a method for configuring the M-PSS, the M-SSS, and theM-PBCH by considering the frame structure type in the NB-LTE systemproposed by the present specification will be described.

As described above, the narrow band (NB)-LTE represents a system forsupporting low complexity and low power consumption having a systembandwidth (BW) corresponding to 1 physical resource block (PRB) or 1 RBof the LTE system.

That is, the NB-LTE system may be primarily used as a communication modefor implementing the IoT by supporting a device (alternatively,terminal) such as machine-type communication (MTC).

Further, the NB-LTE system uses the same OFDM parameters as the LTEsystem, such as the subcarrier spacing used in the existing LTE system,and the like, and as a result, an additional band may not be allocatedfor the NB-LTE system.

That is, 1 RPB of the legacy LTE system band is allocated for the NB-LTEto efficiently use the frequency.

A physical channel in the NB-LTE system will be defined as theM-PSS/M-SSS, M-PBCH, M-PDCCH/M-EPDCCH, M-PDSCH, and the like andexpressed or called by adding M- or narrowband- (N-) in order todistinguish the NB-LTE system from the LTE in the case of the downlink.

Configuring the M-PSS, the M-SSS, and the M-PBCH in the NB-LTE systemproposed by the present specification may be generally divided into (1)a method for similarly configuring the M-PSS, the M-SSS, and the M-PBCHin different frame structure types (first embodiment) and (2) a methodfor differently configuring the M-PSS, the M-SSS, and the M-PBCH in thedifferent frame structure types (second embodiment).

First Embodiment

The first embodiment provides a method for similarly configuring theM-PSS, the M-SSS, and the M-PBCH in different frame structure types(frame structure type 1, frame structure type 2, frame structure type 3,and the like).

Hereinafter, frame structure type 1 and frame structure type 2 in theLTE system are described as the different frame structure types as anexample, but are not limited thereto and may be extensively applied evento other cases.

Further, the methods proposed by the present specification may beapplied even to a stand-alone system and a guard-band system in additionto the in-band system.

One of methods for configuring the M-PSS, the M-SSS, the M-PBCH, and thelike to be used for both frame structure type 1 and frame structure type2 in the NB-LTE system is to similarly configure the M-PSS, the M-SSS,the M-PBCH, and the like regardless of the frame structure type.

That is, when the M-PSS, the M-SSS, the M-PBCH, and the like areconfigured regardless of the frame structure type and the correspondingsignals are transmitted to the terminal, the terminal may find a timingand a frequency estimated through an initial M-PSS.

In addition, the terminal may detect a cell ID of a corresponding cellthrough the M-SSS.

Therefore, the terminal may successfully decode a master informationblock (MIB) transmitted to the M-PBCH (by a base station) through thedetected cell ID.

Herein, it is assumed that the legacy LTE and the NB-LTE uses the sameor similar cell ID.

In addition, the base station may announce a frame structure type (thatis, whether the frame structure type is type 1 or type 2) of a currentcell to the terminal by using one (alternatively, specific informationor a specific field) of information announced through the correspondingMIB.

However, when decoding performance of the terminal, and the like areconsidered, it may be difficult to similarly apply a synchronizationposition to frame structure type 1 and frame structure type 2 due toavailability of a downlink subframe of frame structure type 2.

In this case, a method may also be considered, which distinguishes framestructure type 1 and frame structure type 2 by using a relative distance(alternatively, time) in which the M-PSS and the M-SSS are transmittedor a subframe index in which the M-PSS and the M-SSS are transmitted.

When frame structure type 1 and frame structure type 2 are distinguishedfrom each other by using the subframe index, the base station may addinformation indicating the frame structure type to the M-PBCH, and thelike and transmit the M-PBCH including the corresponding information tothe terminal in order to complement the decoding performance of theterminal.

When the terminal needs to obtain the frame structured type supported bythe cell through blind decoding or blind detection, complexity for theblind decoding or blind detection of the terminal increases.

Accordingly, reduction of other information needs to be relativelyconsidered.

For example, the base station may load some of information on 504 cellIDs on a synchronization sequence and transmit the correspondinginformation and transmit the remaining information through the M-PBCH,and the like rather than transmitting all information on 504 cell IDs tothe terminal.

Alternatively, the base station may not transmit information on a framenumber in which the M-SSS is transmitted to the terminal, but allow theterminal to blindly search for the frame number in which the M-SSS istransmitted or the information on the frame number to the terminal.

As a result, it may be assumed that information which needs to bedistinguished through the M-PSS and the M-SSS is prevented from being‘4096’ or more may be assumed at the time of transmitting thesynchronization signal in a limited bandwidth and limited subframes.

When one radio frame (10 ms) is considered in the legacy LTE system, theM-PSS, the M-SSS, and the M-PBCH may be configured to be transmitted insubframes #0, #4, #5, and #9 other than subframes may be allocated to anMBSFN subframe in frame structure type 1.

Next, a case where the M-PSS, the M-SSS, and the M-PBCH are transmittedin frame structure type 2 will be described.

In case of frame structure type 2, subframes that may be transmittedfrom the base station to the terminal vary in accordance withuplink-downlink configurations as shown in Table 1 above.

In respect to each uplink-downlink configuration, the base station maytransmit the M-PSS, the M-SSS, the M-PBCH, and the like to the terminalin the case of the downlink subframe.

Therefore, in frame structure type 2, the case in which the M-PSS, theM-SSS, and the M-PBCH may be transmitted may be generally divided intocase 1, case 2, and case 3.

First, case 1 is a method in which the M-PSS, the M-SSS, the M-PBCH, andthe like are transmitted in subframes #0, #5, and #9 in theuplink-downlink configurations other than uplink-downlink configuration#0.

Next, case 2 is a method in which the M-PSS, the M-SSS, the M-PBCH, andthe like are transmitted in subframes #0, #4, #5, and #9 in theuplink-downlink configurations other than uplink-downlink configurations#0, #3, and #6.

Next, case 3 as a case to satisfy all uplink-downlink configurations isa method in which the M-PBCH is transmitted in subframe #0 and the M-PSSand the M-SSS are alternately transmitted according to respective cyclesin subframe #5.

Consequently, when the M-PSS, the M-SSS, the M-PBCH, and the like aresimilarly configured regardless of the frame structure type, (1) theM-PSS, the M-SSS, the M-PBCH, and the like may be configured to betransmitted in subframes #0, #5, and #9 or (2) the M-PSS, the M-SSS, theM-PBCH, and the like may be configured to be transmitted in subframes#0, #4, #5, and #9.

(Case 1)

Case 1 is described in detail with reference to FIG. 30.

FIG. 30 is a diagram illustrating one example of M-PSS, M-SSS, andM-PBCH configurations having the same location in a radio frame proposedby the present specification.

Referring to FIG. 30, it can be seen that the M-SSS is transmitted insubframe #0, the M-PBCH is transmitted in subframe #5, and the M-PSS istransmitted in subframe #9.

Further, it can be seen that the M-PSS, the M-SSS, and the M-PBCH arenot allocated to first 3 symbols of the subframe and it can be seen thatthe M-PSS, the M-SSS, and the M-PBCH are not allocated to a resource inwhich an LTE CRS is transmitted.

Further, Case 1 may be divided into three cases (case 1-1, case 1-2, andcase 1-3) as described below.

Case 1-1 is a method in which the M-SSS is transmitted in subframe #0,the M-PBCH is transmitted in subframe #5, and the M-PSS is transmittedin subframe #9 for each radio frame.

In the case of Case 1-1, a radio frame in which the M-PSS, the M-SSS,and the M-PBCH are not transmitted may exist, but when the M-PSS, theM-SSS, and the M-PBCH are transmitted, subframe indexes in whichrespective channels are transmitted may be determined as subframes #9,#0, and #5, respectively.

Herein, the subframe indexes in which the respective channels (M-PSS,M-SSS, and M-PBCH) are transmitted may be changed.

However, when the corresponding channel is transmitted for each radioframe, it may be assumed that the respective channels are transmitted inthe same subframe index.

In Case 1-2, the subframe indexes in which the channels (M-PSS, M-SSS,and M-PBCH) are transmitted may be changed for each radio frame.

Alternatively, one or more channels may be mapped to one subframe indexand when multiple channels are mapped to one subframe index, it may beassumed that different channels are transmitted in different radioframe.

For example, it may be defined that the M-PSS is transmitted in subframe#0 of an odd radio frame and the M-PBCH, and the like are transmitted insubframe #0 of an even radio frame.

Case 1-3 is a method in which the respective channels (M-PSS, M-SSS, andM-PBCH) are configured to be consecutively mapped to multiple subframesin one radio frame.

For example, the M-PSS may be configured to be transmitted to subframe#9 of radio frame #0 and subframe #0 of radio frame #1, the M-SSS may beconfigured to be mapped to subframe #9 of radio frame #1 and subframe #0of radio frame #2, and the M-PBCH may be configured to be mapped tosubframe #9 of radio frame #2 and subframe #0 of radio frame #3.

The mapping (method) of Case 1-3 may be applied to one or multiplechannels and characteristically applied to the mapping of the M-PBCH.

(Case 2)

In Case 2, various methods are available as described below.

First, Case 2-1 is a method in which each of the M-PSS, the M-SSS, andthe M-PBCH is transmitted by selecting one subframe among subframes #0,#4, #5, and #9 so as to prevent the M-PSS, the M-SSS, and the M-PBCHfrom overlapping with each other.

Next, Case 2-2 is a method in which each of each M-PSS and the M-PBCH istransmitted by selecting one subframe among subframes #0, #4, #5, and #9so as to prevent the M-PSS and the M-PBCH from overlapping with eachother and the M-SSS is transmitted by using two remaining subframes.

Case 2-1 may have a structure having the similar form to FIG. 30described above.

When Case 2-2 is described with reference to FIG. 31, the M-PBCH may beconfigured to be transmitted to subframe #0, the M-SSS may be configuredto be transmitted to subframes #4 and #5, and the M-PSS may beconfigured to be transmitted to subframe #9.

In this case, it can be seen that the M-SSS is transmitted by using 6OFDM symbols per subframe differently from FIG. 30.

That is, FIG. 31 is a diagram illustrating another example of M-PSS,M-SSS, and M-PBCH configurations having the same location in the radioframe proposed by the present specification.

Even in Case 2, contents or options described in Case 1 may be applied.

Characteristically, in frame structure type 1, the M-SSS may betransmitted to subframe #4 and in frame structure type 2, the M-SSS maynot be transmitted to subframe #4.

Therefore, the terminal may distinguish frame structure type 1 and framestructure type 2 from each other.

That is, when the M-SSS is mapped to a subframe index which may not betransmitted in frame structure type 2, the terminal may know that theframe structure type of the corresponding base station is type 1.

That is, the terminal may distinguish whether the frame structure typeis type 1 or type 2 according to the position or the subframe index inwhich the M-SSS is transmitted.

Additionally, a case in which both the M-PSS and the M-SSS use twosubframes may be considered.

When the M-PBCH is configured to be transmitted every 10 ms(alternatively, every radio frame), the M-PSS is configured to betransmitted every 20 ms, and the M-SSS is configured to be transmittedevery 80 ms, three following methods may be considered.

A first method is a method in which the M-PBCH is configured to betransmitted to subframe #0, the M-PSS is configured to be transmitted tosubframes #4 and #5 of the even radio frame, and the M-SSS is configuredto be transmitted to subframes #4 and #5 of radio frame #1.

FIG. 32 is a diagram illustrating the first method described above.

That is, FIG. 32 is a diagram illustrating yet another example of theM-PSS, M-SSS, and M-PBCH configurations having the same location in theradio frame proposed by the present specification.

In detail, FIG. 32 is a diagram illustrating one example of M-PSS,M-SSS, and M-PBCH configurations having the same location in 8 radioframes.

Referring to FIG. 32, radio frames #3, #5, and #7 may use alluplink-downlink configurations and radio frames #0, #1, #2, #4, #5, and#6 other than radio frames #3, #5, and #7 may use uplink-downlinkconfigurations #1, #2, #4, and #5.

A second method is a method in which the M-PBCH is configured to betransmitted to subframe #0, the M-PSS is configured to be transmitted tosubframes #5 and #9 of the even radio frame, and the M-SSS is configuredto be transmitted to subframes #5 and #9 of radio frame #1.

FIG. 33 is a diagram illustrating a second method.

That is, FIG. 33 is a diagram illustrating still yet another example ofthe M-PSS, M-SSS, and M-PBCH configurations having the same location inthe radio frame proposed by the present specification.

Referring to FIG. 33, radio frames #3, #5, and #7 may use alluplink-downlink configurations and radio frames #0, #1, #2, #4, #5, and#6 other than radio frames #3, #5, and #7 may use uplink-downlinkconfigurations #1 to #6.

A third method is a method in which the M-PBCH is configured to betransmitted to subframe #5, the M-PSS is configured to be transmitted tosubframe #9 of the even radio frame and subframe #0 of the odd radioframe, and the M-SSS is configured to be transmitted to subframe #9 ofradio frame #1 and subframe #0 of radio frame #2.

FIG. 34 is a diagram illustrating a third method.

That is, FIG. 34 is a diagram illustrating still yet another example ofthe M-PSS, M-SSS, and M-PBCH configurations having the same location inthe radio frame proposed by the present specification.

Referring to FIG. 34, in the third method, radio frames #3, #5, and #7may use all uplink-downlink configurations like the second method (FIG.33) and radio frames #0, #1, #2, #4, #5, and #6 other than radio frames#3, #5, and #7 may use uplink-downlink configurations #1 to #6.

Additionally, the frame structure types may be defined to bedistinguished by differently setting the sequence to configure theM-PSS.

In this regard, the Golay sequence described in FIG. 23 and the methodfor configuring and transmitting the M-PSS by using the Golay sequencewill be described in brief.

Golay Sequence

Golay complementary sequences are pairs of binary codes belonging to abigger family of signals called complementary pairs, which consists oftwo codes of the same length n, whose auto-correlation functions haveside-lobes equal in magnitude but opposite in sign.

Summing them up results in a composite auto-correlation function with apeak of 2n and zero side-lobes.

There are several essentially different algorithms for generating Golaypairs.

Let the variables ai and bi (i=1,2, . . . , n) be the elements of twon-long complementary sets, which are equal to either +1 or −1.A=a1,a2, . . . ,an, B=b1,b2, . . . ,bn  [Equation 10]

The ordered pair (A; B) are Golay sequences of length n if and only iftheir associated polynomials areA(x)=a ₁ +a ₂ x+ . . . +a _(n) x ⁻¹B(x)=b ₁ +b ₂ x+ . . . +b _(n) x ^(n−1)  [Equation 11]

And satisfy the identity,A(x)A(x ⁻¹)+B(x)B(x ⁻¹)=2n  [Equation 12]

in the Laurent polynomial ring Z[x, x−1].

Let the auto-correlation function NA and NB, corresponding to thesequences A and B respectively, be defined by the following expressions:N _(A)(j)=Σ_(i∈Z) a _(i) a _(i+j) ,N _(B)(j)=Σ_(i∈Z) b _(i) b_(i+j)  [Equation 13]

where the set ak=0 if k∉(1, . . . , n). Now the condition Equation 12can be substituted by the sum NA+NB, and

$\begin{matrix}{{{N_{A}(j)} + {N_{B}(j)}} = \left\{ \begin{matrix}{{2N},} & {j = 0} \\{0,} & {j \neq 0}\end{matrix} \right.} & \left\lbrack {{Equation}\mspace{14mu} 14} \right\rbrack\end{matrix}$

The sum of both auto-correlation functions is 2N at j=0 and zerootherwise.

Let the variables a(i) and b(i) be the elements (i=0,1, . . . , 2n−1) oftwo complementary sequence with elements 1 and −1 of length 2n:a ₀(i)=δ(i),b ₀(i)=δ(i)  [Equation 15]a _(n)(i)=a _(n−1)(i)+b _(n−1)(i−2^(n−1)),b _(n)(i)=a _(n−1)(i)+b_(n−1)(i−2^(n−1))  [Equation 16]

where δ(i) is the Kronecker delta function. Expression 17 shows that oneach step new elements of the sequences are produced by concatenation ofelements a_(n)(i) and b_(n)(i) of length n.

In transmitting the M-PSS (alternatively, N-PSS) in the NB-LTE system,the M-PSS (alternatively, N-PSS) may be transmitted by using multipleOFDM symbols.

In this case, as the sequence transmitted to the OFDM symbol, the samesequence may be repeatedly transmitted and the sequence may betransmitted by multiplying each OFDM symbol by a specific over sequence.When this is expressed by the drawing, a structure illustrated in FIG.35 is provided.

That is, FIG. 35 illustrates one example of an M-PSS transmissionstructure to which the method proposed by the present specification canbe applied.

When 1 PRB is assumed, the maximum length of the sequence which may betransmitted to one OFDM symbol is 12 on the assumption of the 15 KHzsubcarrier spacing.

Hereinafter, for easy description, 1 PRB and 15 KHz subcarrier spacingare assumed.

Further, ‘PSS’ expressed hereinbelow which means the PSS in the NB-LTEsystem may be called or expressed as M-PSS, N-PSS, NB-PSS,narrowband-PSS, and the like.

When the PSS is detected by a receiver (alternatively, the terminal),implementation processed in the time domain is general by consideringthe complexity of the calculation.

In order to obtain time/frequency synchronization through the PSS,correlation is acquired by applying a sliding window to the PSSsequence.

Since the same sequence is transmitted every OFDM symbol, the PSStransmission structure illustrated in FIG. 35 may show a relativelylarge correlation value by using the OFDM symbol length as the period.

Therefore, a correlation characteristic may be improved by increasingthe period in which the relatively large correlation value is output byusing a condition of Equation 14 of a complementary Golay sequence.

Further, the cover sequence is applied every OFDM symbol to furtherimprove the correlation characteristic.

In this case, a method of transmitting the PSS by using thecomplementary Golay sequence is described below.

(Method 1)

First, Method 1 is a method that a complementary Golay sequence pair isalternately disposed in the OFDM symbol.

For example, when N=6 OFDM symbols is assumed, a(n) is transmitted toOFDM symbol 1 and b(n) is transmitted to OFDM symbol 2.

In this case, c(n) may be applied by taking length 6 as an m-sequence oflength 7.

In this case, it is preferable that the number of OFDM symbolstransmitting the PSS is an even number.

When the complementary Golay sequence is assumed as a binary sequence,an available sequence length is 2a10b26c (a, b, and c are integers of 0or more). 0∥⊏∥-.

If there is only 12 available resources in one OFDM symbol, theavailable Golay sequence length may be 10.

One example of the complement Golay sequence pair of length 10 isa(n)=[1 1−1 −1 1 1 1−1 1−1] and b (n)=[1 1 1 1 1−1 1−1 −1 1].

Among the OFDM symbols, the OFDM symbol filled with 0 is transmitted toREs to which no sequence is allocated.

When a non-binary complementary Golay sequence is assumed, the sequencepair exists without a limit in length, and as a result, sequence pairsa(n) and b(n) with a length of 12 may be transmitted while beingdisposed in the OFDM symbol in the same manner disposed and transmittedcan be transmitted in an OFDM symbol in the same manner.

Correlation characteristics for various c(n) patterns with Sequencepairs a(n) and b(n) with the length of 10 are illustrated in FIG. 36.

FIG. 36 is a diagram illustrating correlation characteristics dependingon various cover sequence patterns.

As another method, when the PSS is transmitted to odd OFDM symbols, thePSS may be transmitted in such a manner that one sequence of thesequence pair is transmitted once more.

For example, when N=7 OFDM symbols, a(n), b(n), a(n), b(n), a(n), b(n),and a(n) may be transmitted while being disposed in the OFDM symbol inthe order of a(n), b(n), a(n), b(n), a(n), b(n), and a(n).

(Method 2)

Next, Method 2 is a method that all of the complementary Golay sequencepairs are disposed in one OFDM symbol.

Method 2 may be divided into (1) Method 2-1 and (2) Method 2-2 asdescribed below.

First, Method 2-1 is a method in which a sequence corresponding to ½ ofone OFDM symbol is generated and disposed.

For example, when N=6 OFDM symbols is assumed, non-binary complementaryGolay sequences a(n) and b(n) having a length of 6 may be generated,a(n) ma be allocated to ½ of available REs of one OFDM symbol, and b(n)may be transmitted while being allocated to the remaining ½ REs.

In this case, a(n) may be allocated to former ½ REs and b(n) may beallocated to latter ½ REs.

Next, Method 2-2 is a method in which the OFDM symbols a(n) and b(n) aretransmitted through superposition.

For example, Method 2-2 is a method in which when N=6 OFDM symbols, thebinary/non-binary complementary Golay sequence with the length of 10/12is generated and a(n)+b(n) is calculated and transmitted.

(Method 3)

Next, Method 3 is a method in which L or more complementary Golaysequences are disposed and transmitted.

In this case, the number of OFDM symbols transmitting the PSS needs tosatisfy a condition in which L is multiple.

For example, when L=3 and N=6, complementary Golay sequence la(n),lb(n), and lc(n) having the length of 10 or 12 may be sequentiallytransmitted while being disposed in the OFDM symbol.

That is, la(n), lb(n), lc(n), la(n), lb(n), and lc(n) are disposed inthe order of la(n), lb(n), lc(n), la(n), lb(n), and lc(n) andtransmitted by applying cover sequence c(n).

After the PSS is detected, the terminal detects the SSS to acquire cellid detection, a subframe index in which the SSS is transmitted, andinformation on other system information.

The SSS expressed hereinbelow may be interpreted similarly to M-SSS,N-SSS, NB-SSS, and the like.

The transmission structure of the SS may be configured as illustrated inFIG. 37.

That is, FIG. 37 illustrates one example of an SSS transmissionstructure to which the method proposed by the present specification canbe applied.

Referring to FIG. 37, a sequence having a length of M is generated andthe generated sequence having the length of M is multiplied by ascramble sequence having the length of M.

Thereafter, a signal multiplied by the scrambling sequence is dividedinto sequences having a length of L (M>=L) and disposed in correspondingOFDM symbols so as to be transmitted to N OFDM symbols and transmittedby scrambling sequence s(n).

For example, when M=72, L=12, and N=6 are assumed, a sequence having alength of 72 is divided into 6 sequences having the length of 12 to betransmitted to 6 OFDM symbols, respectively.

In this case, a method for designing an SSS sequence in order totransmit the corresponding information is described below.

(Method 1)

In Method 1, two Zadoff-Chu sequences (SSS1 and SSS2) having a length ofM/2 are generated and thereafter, (In this case, a root index is fixedto a specific value. For example, the root index may be fixed to 1.)concatenated to generate a sequence having a length of M.

Information on the cell id may be expressed by using a combination (CS1and CS2) of cyclic shift values of two generated sequences.

In addition, the scrambling sequence having the length of M is generatedby functions of information on a subframe in which the SSS istransmitted and system information.

The sequence having the length L is divided to be disposed in N OFDMsymbols.

For example, when M=72, L=12, and N=6 are assumed, two Zadoff-Chusequences having a length of 36 are concatenated by generating thecyclic shift value expressing the cell id.

A PN sequence having a length of 128 is divided into sequences havingthe length of 12 to be disposed in the corresponding OFDM symbols inorder to transmit the scrambling sequence having a length of c to 6 OFDMsymbols.

In the m-sequence having the length of 127 generated by initializing thescrambling sequence to the system information and the subframeinformation like c_(init)=N_(sys)2⁴+N_(index) ^(subframe), the 72scrambling sequence is generated by applying a predetermined offset tobe multiplied by the concatenated Zadoff-Chu sequences.

As another method, the offset value is generated by the function of thesubframe information and the system information with respect to them-sequence having the length of 127, which is generated byinitialization with a predetermined value (e.g., cinit=1) to generatethe scrambling sequence having the length of 72.

In this case, when the offset value is larger than 55, the scramblingsequence is generated by counting the offset value again in a firstsequence by a first circular shift method.

That is, the scrambling sequence may be generated by a method such ass(k), . . . , s(127), s(1), . . . .

(Method 2)

In Method 2, complementary Golay sequences (SSS1 and SS2) having thelength of M/2 is generated and thereafter, concatenated to generate theM-length sequence.

In this case, one sequence in the complementary Golay sequence pair maybe used as the SS1 and the SS2 or one sequence in the sequence pair maybe allocated to SS1 and the other one may be allocated to SSS2.

The information on the cell id may be expressed by using the combination(CS1 and CS2) of the cyclic shift values of two generated sequences.

In addition, the scrambling sequence having the length of M is generatedby the functions of the information on the subframe in which the SSS istransmitted and the system information.

The sequence having the length L is divided into N to be disposed in NOFDM symbols.

0 may be allocated to some REs of the OFDM symbol due to a limit inlength of the complementary Golay sequence pair according to acombination of M, L, and N.

Based on the aforementioned contents, the frame structure types may bedefined to be distinguished by differently setting the sequence toconfigure the M-PSS.

For example, the M-PSS transmitted to one or two subframes is configuredby a short-Zadoff-Chu (ZC) sequence or long-ZC sequence to betransmitted.

For example, in the case of the short-Zadoff-Chu (ZC) sequence, each ofthe short ZC sequences may be mapped to one OFDM symbol.

In addition, in the case of the long-ZC sequence, the long-ZC sequencemay be mapped to 11 OFDM symbols.

In this case, it may be considered that the base station transmits thesequences to have a complex conjugate relationship with each other asforms of the transmitted sequences in order for the terminal toefficiently find a timing offset and a frequency offset.

The complex conjugate relationship is formed by controlling the rootindex.

For example, in the case of frame structure type 1, the M-PSS may betransmitted by using sequences configured by two different root indexesA and B in the order of A and B.

Herein, the root indexes A and B are integers which are not larger thanthe corresponding sequence length and a ZC sequence configured by rootindex A and a ZC sequence configured by root index B have the complexconjugate relationship with each other.

In addition, in the case of frame structure type 2, the M-PSS may betransmitted by using sequences configured by two different root indexesB and A in the order of B and A.

One example of the method for transmitting the M-PSS by using the shortZC sequence is illustrated in FIG. 38 and one example of the method fortransmitting the M-PSS by using the long ZC sequence is illustrated inFIG. 39.

That is, FIGS. 38 and 39 illustrate one example of a method fortransmitting the M-PSS by using different sequences for each framestructure type proposed by the present specification.

As illustrated in FIGS. 38 and 39, the frame structure types may bedistinguished by setting the sequences differently, but configured to beused for a purpose of distinguishing operation modes (i.e., in-band,guard band, and stand-alone) by setting the sequences differently.

Second Embodiment

The second embodiment provides a method for configuring the M-PSS, theM-SSS, and the M-PBCH in different frame structure types (framestructure type 2, frame structure type 2, frame structure type 3, andthe like) differently from each other.

Another method of the methods for configuring the M-PSS, the M-SSS, theM-PBCH, and the like so that the NB-LTE system is used for both framestructure type 1 and frame structure type 2 defined in the LTE is todifferently configure the M-PSS, the M-SSS, the M-PBCH, and the likeaccording to each frame structure type differently from the firstembodiment described above.

That is, when the M-PSS, the M-SSS, and the M-PBCH are configureddifferently from each other according to the frame structure type, theterminal may find the timing and the frequency estimated through theinitial M-PSS and attempts blind detection with respect to candidatesubframes in which the M-SSS may be transmitted, and as a result, theterminal may determine whether the frame structure type operated by thebase station is type 1 or type 2.

When the frame structure type is type 1 in the first embodimentdescribed above, the M-PSS, the M-SSS, and the M-PBCH may be transmittedin subframes #0, #4, #5, and #9.

Further, when the frame structure type is type 2, it can be seen thatthe M-PSS, the M-SSS, and the M-PBCH may be transmitted in subframes #0,#5, and #9 in the uplink-downlink configurations other thanuplink-downlink configuration #0.

Alternatively, the M-PSS, the M-SSS, and the M-PBCH may be transmittedeven in subframes #0, #4, #5, and #9 other than uplink-downlinkconfigurations #0, #3, and #6.

Alternatively, by considering all uplink-downlink configurations, theM-PBCH may be transmitted in subframe #0 and the M-PSS and the M-SSS maybe alternately transmitted in subframe #5.

Hereinafter, the second embodiment, that is, various methods thatconfigure (alternatively, set or design) the M-PSS, the M-SSS, theM-PBCH, and the like differently from each other according to the framestructure type will be described.

(Method 1)

Method 1 is a method in which all of the M-PSS, the M-SSS, and theM-PBCH are transmitted through different subframes.

FIG. 40 is a diagram illustrating one example of M-PSS, M-SSS, andM-PBCH configurations having different locations in a radio frameproposed by the present specification.

That is, Method 1 given above is described with reference to FIG. 40.

In the case of frame structure type 1, it can be seen that the M-PBCH isconfigured to be transmitted in subframe #0, the M-SSS is configured tobe transmitted in subframe #4, and the M-PSS is configured to betransmitted in subframe #5.

In the case of frame structure type 2, it can be seen that the M-SSS isconfigured to be transmitted in subframe #0, the M-PBCH is configured tobe transmitted in subframe #5, and the M-PSS is configured to betransmitted in subframe #9.

In this case, the terminal may find the timing and the frequencyestimated by detecting the M-PSS and determines in which subframe of theprevious subframe and the just subsequent subframe the M-SSS istransmitted by attempting the blind detection, and as a result, theterminal may determine whether the frame structure type currentlyoperated by the base station is type 1 or type 2.

Therefore, when the terminal accurately determines the frame structuretype operated by the bases station, the terminal may previously knowthat the M-PBCH is transmitted through subframes #0 and #5 according toeach frame structure type.

Accordingly, the terminal may decode the MIB transmitted through theM-PBCH.

An advantage of Method 1 is that the terminal may more accuratelydetermine the frame structure type.

That is, when the terminal determines the frame structure type afterdetecting the M-PSS, the terminal may determine the frame structure typeby using only the location of the subframe in which the M-SSS istransmitted, but furthermore, the terminal may determine the framestructure type by more deliberately or accurately performing the blinddetection by considering even the location of the subframe in which theM-PBCH is transmitted in addition to the location of the subframe inwhich the M-SSS is transmitted.

However, in Method 1, detection complexity (or calculation complexity)may increase in terms of the terminal according to a situation.

(Method 2)

Method 2 is a method in which any one of the M-PSS, the M-SSS, and theM-PBCH is configured to be transmitted through the same subframe and twoothers are configured to be transmitted through different subframes.

FIG. 41 is a diagram illustrating Method 2.

That is, FIG. 41 is a diagram illustrating another example of the M-PSS,M-SSS, and M-PBCH configurations having different locations in the radioframe proposed by the present specification.

Method 2 given above is described with reference to FIG. 41.

It can be seen that the M-PBCH is configured to be continuouslytransmitted in subframe #0 regardless of the frame structure type.

In addition, in the case of frame structure type 1, the M-SSS isconfigured to be transmitted in subframe #4 and the M-PSS is configuredto be transmitted in subframe #5.

Moreover, in the case of frame structure type 2, the M-SSS is configuredto be transmitted in subframe #5 and the M-PSS is configured to betransmitted in subframe #9.

In Method 2, since the M-PBCH is continuously transmitted through thesame subframe, the location of the M-PBCH need not be distinguishedaccording to the frame structure type, but the frame structure typeneeds to be distinguished through the M-PSS detection and the M-SSSblind detection.

The advantage of Method 2 is that since one of the M-PSS, the M-SSS, andthe M-PBCH is fixed, it is advantageous to the terminal in terms of thedetection complexity.

For example, as illustrated in FIG. 38, when it is assumed that theM-PBCH is fixed, the terminal may detect the M-PSS and determine thelocation of the subframe in which the M-PBCH is transmitted by using theestimated timing and frequency information.

Further, the terminal may determine the frame structure type bydetermining how many subframes the M-PBCH and the M-PSS are spaced apartfrom each other by.

Additionally, the terminal may determine the frame structure type byconsidering both positional information of the subframe in which theM-PBCH is transmitted and subframe information in which the M-SSS istransmitted.

(Method 3)

Method 3 is a method in which only one of the M-PSS, the M-SSS, and theM-PBCH is configured to be transmitted through different subframes andtwo others are configured to be transmitted through the same subframe.

FIG. 42 is a diagram illustrating Method 3.

That is, FIG. 42 is a diagram illustrating yet another example of theM-PSS, M-SSS, and M-PBCH configurations having different locations inthe radio frame proposed by the present specification.

When Method is described with reference to FIG. 42, the M-PBCH may beconfigured to be continuously transmitted in subframe #0 and the M-PSSmay be configured to be continuously transmitted in subframe #5regardless of the frame structure type.

Moreover, in the case of frame structure type 1, the M-SSS may beconfigured to be transmitted in subframe #4 and, in the case of framestructure type 2, the M-SSS may be configured to be transmitted insubframe #9.

Even in Method 3, since the M-PBCH is continuously transmitted throughthe same subframe similarly to the case of FIG. 38 described above, thelocation of the M-PBCH need not be distinguished according to the framestructure type, but the frame structure type needs to be distinguishedthrough the M-PSS detection and the M-SSS blind detection.

When Method 3 is used, after the terminal detects the M-PSS, since thelocation of the subframe in which the M-PBCH is transmitted isdetermined, the terminal may know the corresponding location.

In this case, when the blind detection for the M-PBCH is not required,an effect of reducing complexity is achieved in terms of the terminal.

Further, since the terminal may determine the location by detecting theM-PSS and thereafter, performing the blind detection of only thelocation of the subframe in which the M-SSS is transmitted, the effectof reducing the complexity of the terminal is achieved.

(Method 4)

Method 4 is a method that distinguishes whether the frame structure typeis type 1 or type 2 by considering a period in which the M-PSS istransmitted or the number of subframes transmitted in one radio frame.

For example, the M-PSS may be transmitted every 20 ms and in type 1,when the M-PSS is transmitted once, the M-PSS is transmitted through twosubframes and in type 2, the M-PSS may be transmitted throughout onesubframe.

Alternatively, instead of the M-PSS, a transmission frequency number ora transmission period of the M-SSS may be used.

More characteristically, the period in which the M-PSS is transmittedmay be used for distinguish the operation modes (e.g., the stand-alonethe in-band) or used for announcing a data rate matching pattern.

The data rate matching pattern may indicate that all REs are availableor some REs are not available due to the legacy signal.

As such, when the transmission period is announced, the M-PSS may betransmitted by using different numbers of symbols or different durationsin the case of mapping the M-SSS.

In this case, the M-SSS may be transmitted in the form of repetition.

In the case of the in-band, type 1 and type 2 may be distinguished fromeach other according to the operation and type 1 and type 2 may bedistinguished from each other with the period or frequency of the M-SSSin the case of the in-band.

(Method 5)

Method 5 is a method that distinguishes the frame structure type withtransmission frequencies.

For example, in the case of type 1, the M-PSS and the M-SSS may betransmitted at the same frequency and in the case of type 2, the M-PSSand the M-SSS may be transmitted at different frequencies.

(Method 6)

Method 6 is a method in which the M-PSS, the M-SSS, and the M-PBCH areconfigured to be transmitted by using different subframe numbersaccording to the frame structure type.

FIG. 43 is a diagram illustrating Method 6.

That is, FIG. 43 is a diagram illustrating yet another example of theM-PSS, M-SSS, and M-PBCH configurations having different locations inthe radio frame proposed by the present specification.

In detail, FIG. 43 is a diagram illustrating the M-PSS, M-SSS, andM-PBCH configurations having different locations in 2 radio frames.

When Method 6 is described with reference to FIG. 43, in the case offrame structure type 1, the M-PBCH may be configured to be transmittedin subframe #0, the M-SSS may be configured to be transmitted insubframe #4, and the M-PSS may be configured to be transmitted insubframe #5.

In addition, in the case of frame structure type 2, the M-PBCH may beconfigured to be transmitted in subframe #0, the M-PSS may be configuredto be transmitted in subframe #5 for former 10 ms and the M-SSS may beconfigured to be transmitted in subframe #5 for latter 10 ms (byconsidering the M-PSS and the M-SSS having a period of 20 ms).

That is, in this method, in the case of frame structure type 1, theM-PSS, the M-SSS, and the M-PBCH are transmitted by using 6 subframesand in the case of frame structure type 2, the M-PSS, the M-SSS, and theM-PBCH are transmitted by using 4 subframes for 20 ms.

Method 6 has the advantage in that Method 6 may be applied to alluplink-downlink configurations in the case of frame structure type 2.

FIG. 44 is a flowchart illustrating one example of a method fortransmitting an M-PSS, an M-SSS, and an M-PBCH by considering the framestructure type proposed by the present specification.

First, the terminal receives a narrow band synchronization signal fromthe base station (S4410).

The narrow band synchronization signal may include a narrow band primarysynchronization signal and a narrow band secondary synchronizationsignal.

Further, the narrow band primary synchronization signal and the narrowband secondary synchronization signal may be transmitted in differentsubframes.

The narrow band primary synchronization signal may be transmitted in a6^(th) subframe of the radio frame.

The transmission periods of the narrow band primary synchronizationsignal and the narrow band secondary synchronization signal may be setto be different from each other.

In particular, the transmission period of the narrow band secondarysynchronization signal may be set to 20 ms.

The narrow band secondary synchronization signal may be transmittedthrough 12 subcarriers.

The narrow band synchronization signal may be generated by using aZadoff-Chu (ZC) sequence.

The narrow band primary synchronization signal may be generated based ona first ZC sequence and a second ZC sequence having different rootindexes.

The first ZC sequence and the second ZC sequence may be mapped tosymbols to which the narrow band primary synchronization signal istransmitted, respectively.

Further, the frame structure type supported by the base station may bedistinguished according to the order in which the first ZC sequence andthe second ZC sequence are mapped to the symbols, respectively.

Alternatively, the method is a method in which the narrow band primarysynchronization signal is generated based on a ZC sequence having aspecific length and the ZC sequence having the specific length is mappedto the symbols to which the narrow band primary synchronization signalis transmitted.

Thereafter, the terminal acquires time synchronization and frequencysynchronization with the base station based on the received narrow bandsynchronization signal and detects an identifier of the base station(S4420).

Thereafter, the terminal receives a narrow band broadcast channel fromthe base station based on the detected identifier of the base station(S4430).

The narrow band synchronization signal and the narrow band broadcastchannel are received through a narrow band (NB) and the narrow bandincludes a system bandwidth of 180 kHz and includes 12 subcarriersdisposed at an interval of 15 kHz.

Further, the narrow band broadcast channel is transmitted in a firstsubframe of the radio frame.

The narrow band synchronization signal and the narrow band broadcastchannel are not transmitted in at least one resource in which areference signal (RS) is transmitted.

The narrow band synchronization signal and the narrow band broadcastchannel are not transmitted in first three symbols of the first subframeand the sixth subframe.

Further, the first subframe and the sixth subframe are subframes whichare not configured as a multicast broadcast single frequency network(MBSFN).

In addition, the narrow band synchronization signal and the narrow bandbroadcast channel may be transmitted through 11 orthogonal frequencydivision multiple access (OFDM) symbols.

Additionally, the terminal may verify the frame structure type supportedby the base station based on at least one of the narrow bandsynchronization signal and the narrow band broadcast channel.

General Apparatus to which Present Invention can be Applied

FIG. 45 is a diagram illustrating one example of an internal blockdiagram of a wireless communication apparatus to which the methodsproposed by the present specification can be applied.

Referring to FIG. 45, a wireless communication system includes a basestation 4510 and multiple terminals 4520 positioned in a region of thebase station 4510.

The base station 4510 includes a processor 4511, a memory 4512, and aradio frequency (RF) unit 4513. The processor 4511 implements afunction, a process, and/or a method which are proposed in FIGS. 1 to 44given above. The layers of the radio interface protocol may beimplemented by the processor 4511. The memory 4512 is connected with theprocessor 4511 to store various pieces of information for driving theprocessor 4511. The RF unit 4513 is connected with the processor 4511 totransmit and/or receive a radio signal.

A terminal 4520 includes a processor 4521, a memory 4522, and an RF unit4523. The processor 4521 implements a function, a process, and/or amethod which are proposed in FIGS. 1 to 44 given above. The layers ofthe radio interface protocol may be implemented by the processor 4521.The memory 4522 is connected with the processor 4521 to store variouspieces of information for driving the processor 4521. The RF unit 4523is connected with the processor 4521 to transmit and/or receive a radiosignal.

The memories 4512 and 4522 may be positioned inside or outside theprocessors 4511 and 4521 and connected with the processors 4511 and 4521through various well-known means.

Further, when the base station 4510 and/or the terminal 4520 may haveone antenna or multiple antennas.

The example of the method for transmitting the uplink signal thewireless communication system of the present specification, which isapplied to the 3GPP LTE/LTE-A system is primarily described, but themethod can be applied to various wireless communication systemsincluding a 5G system, and the like in addition to the 3GPP LTE/LTE-Asystem.

The aforementioned embodiments are acquired by combining the componentsand features of the present invention in a predetermined format. Itshould be considered that each component or feature is selective if notadditionally clearly mentioned. Each component or feature may beimplemented while being not combined with other components or features.Further, some components and/or features are combined to configure theembodiment of the present invention. A sequence of the operationsdescribed in the embodiments of the present invention may be changed.Some components or features of any embodiment may be included in anotherembodiment or replaced with corresponding components or features ofanother embodiment. It is apparent that claims having no clear quotingrelation in the claims are combined to configure the embodiment or maybe included as new claims by correction after application.

The embodiments of the present invention may be implemented by variousmeans, for example, hardware, firmware, software, or combinationsthereof. In the case of the implementation by the hardware, methodsaccording to embodiments of the present invention may be implemented byone or more Application Specific Integrated Circuits (ASICs), DigitalSignal Processors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, micro-controllers, micro-processors,and the like.

When the embodiments are implemented by the firmware or the software,the embodiments of the present invention may be implemented in the formof a module, a procedure, a function, and the like to perform thefunctions or operations described above. A software code may be storedin the memory and executed by the processor. The memory may bepositioned inside or outside the processor and send and receive data toand from the processor by various means which is already known.

It is apparent to those skilled in the art that the present inventionmay be implemented in another specific form within the scope withoutdeparting from the essential feature of the present invention.Therefore, the detailed description should not limitedly be analyzed inall aspects and should be exemplarily considered. The scope of thepresent invention should be determined by rational interpretation of theappended claims and all changes are included in the scope of the presentinvention within the equivalent scope of the present invention.

What is claimed is:
 1. A method for transceiving a signal in a wirelesscommunication system supporting narrow-band (NB)-LTE, which is performeda terminal, the method performed by a terminal and comprising:receiving, from a base station, a narrow band synchronization signal;acquiring time synchronization and frequency synchronization with thebase station based on the narrow band synchronization signal anddetecting an identifier of the base station; and receiving, from thebase station, broadcast information based on the detected identifier ofthe base station, wherein the narrow band synchronization signal and thebroadcast information are received through a narrow band (NB), whereinthe narrow band has a system bandwidth of 180 kHz and includes 12subcarriers disposed at an interval of 15 kHz, wherein the narrow bandsynchronization signal includes a narrow band primary synchronizationsignal and a narrow band secondary synchronization signal, wherein thenarrow band primary synchronization signal and the narrow band secondarysynchronization signal are transmitted in different subframes, andwherein the broadcast information is transmitted in a first subframe ofa radio frame.
 2. The method of claim 1, wherein the narrow band primarysynchronization signal is transmitted in a 6th subframe of the radioframe.
 3. The method of claim 1, wherein the narrow band synchronizationsignal and the broadcast information are not transmitted in at least oneresource in which a reference signal (RS) is transmitted.
 4. The methodof claim 2, wherein the narrow band synchronization signal and thebroadcast information are not transmitted in first three symbols of thefirst subframe and the sixth subframe.
 5. The method of claim 2, whereinthe first subframe and the sixth subframe are subframes which are notconfigured as a multicast broadcast single frequency network (MBSFN). 6.The method of claim 1, wherein transmission periods of the narrow bandprimary synchronization signal and the narrow band secondarysynchronization signal are set to be different from each other.
 7. Themethod of claim 6, wherein the transmission period of the narrow bandsecondary synchronization signal is set to 20 ms.
 8. The method of claim1, wherein the narrow band synchronization signal and the broadcastinformation are transmitted through 11 orthogonal frequency divisionmultiple access (OFDM) symbols.
 9. The method of claim 8, wherein thenarrow band secondary synchronization signal is transmitted through 12subcarriers.
 10. The method of claim 1, further comprising: checking aframe structure type supported by the base station based on at least oneof the narrow band synchronization signal and the broadcast information.11. The method of claim 10, wherein the narrow band synchronizationsignal is generated by using a Zadoff-Chu (ZC) sequence.
 12. The methodof claim 11, wherein the narrow band primary synchronization signal isgenerated based on a first ZC sequence and a second ZC sequence havingdifferent root indexes.
 13. The method of claim 12, wherein the first ZCsequence and the second ZC sequence are mapped to symbols to which thenarrow band primary synchronization signal, respectively.
 14. The methodof claim 13, wherein the frame structure type supported by the basestation is distinguished according to the order in which the first ZCsequence and the second ZC sequence are mapped to the symbols,respectively.
 15. The method of claim 11, wherein the narrow bandprimary synchronization signal is generated based on a ZC sequencehaving a specific length, and the ZC sequence having the specific lengthis mapped to the symbols in which the narrow band primarysynchronization signal is transmitted.
 16. A terminal for transceiving asignal in a wireless communication system supporting narrow-band(NB)-LTE, the terminal comprising: a radio frequency (RF) unitconfigured to transceive a wireless signal; and a processor functionallyconnected with the RF unit, wherein the processor is configured to:receive, from a base station a narrow band synchronization signal,acquire time synchronization and frequency synchronization with the basestation based on the narrow band synchronization signal and detect anidentifier of the base station, and receive, from the base station,broadcast information based on the detected identifier of the basestation, wherein the narrow band synchronization signal and thebroadcast information are received through a narrow band (NB), whereinthe narrow band has a system bandwidth of 180 kHz and includes 12subcarriers disposed at an interval of 15 kHz, wherein the narrow bandsynchronization signal includes a narrow band primary synchronizationsignal and a narrow band secondary synchronization signal, wherein thenarrow band primary synchronization signal and the narrow band secondarysynchronization signal are transmitted in different subframes, andwherein the broadcast information is transmitted in a first subframe ofa radio frame.